Method for inhibiting bud growth of plants
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. Ser. No. 631,359, filed Nov. 12, 1975, now U.S. Pat. No. 4,067,718. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to the use of imidazoisoindolediones and dihydroimidazoisoindolediones as plant growth regulants. 
     2. Description of the Prior Art 
     The compounds useful in this invention are disclosed in Marinus Los&#39; copending U.S. applications Ser. Nos. 631,356 and 631,357, both filed Nov. 12, 1975 and now U.S. Pat. Nos. 4,041,045 and 4,017,510 respectively. Intermediates used in the manufacture of the compounds useful in the invention are disclosed in Netherlands Pat. No. 7,311,503, published Feb. 25, 1974 and assigned to the American Cyanamid Company. The corresponding U.S. application is copending Ser. No. 382,418 filed July 25, 1973, now U.S. Pat. No. 3,940,419. 
     SUMMARY OF THE INVENTION 
     The invention relates to a method for controlling plant growth by applying to the foliage thereof or to soil containing seeds of the plant, a plant-growth-regulating amount of a compound of the formula: ##STR1## wherein X is H, CH 3 , NO 2 , Cl, OCH 3  or SCH 3  ; R 1  may be phenyl, vinyl, or alkyl C 1  -C 4  ; R 2  represents alkyl C 1  -C 4 , providing that when R 1  is alkyl the sum of the carbon atoms in the groups represented by R 1  and R 2  is 5 to 7, and when R 1  and R 2  are taken together with the carbon to which they are attached, they may form cycloalkyl C 5  -C 6  optionally substituted with methyl; Y represents hydrogen; and the optical and stereoisomes thereof. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred compounds for use as plant growth regulators are represented by formulas I and II above, wherein X is H, Cl, CH 3  or --SCH 3  ; Y is hydrogen; and R 1  and R 2  are alkyl C 1  -C 4  provided that the sum of the carbon atoms represented thereby is 4 or 5, or when R 1  and R 2  are taken together with the carbon to which they are attached they represent cycloalkyl C 5  -C 6 . 
     The compounds of the present invention are highly effective plant growth regulating agents. They may be used effectively for controlling the relative stem growth of both monocotyledonous and dicotyledonous plants by application thereof to the foliage of the plants, or by application to soil containing seeds of the plants. Generally, one treatment is effective on the total growth of the plant; however, repeated treatments are frequently found to increase the extent of the effect. The most characteristic growth alterations brought about by the treatment (using formula I or II compounds where X is a substituent other than chloro) are shorter, thicker stems, reduction in tillering and reduction in sucker growth. As such, the compounds of this invention (as defined above) are found to be particularly useful for treating roadside plantings, where it is desirable to reduce the number of grass cuttings and shrub prunings needed for proper grooming during the growing season. These compounds are also useful for dwarfing cereal grains such as rice, barely and wheat, and preventing lodging thereof. Usually, about 0.25 to 4.0 pounds per acre or 0.28 to 4.48 kg/hectare, and preferably 1.12 to  4.48 kg/hectare of the active compound is effective for achieving this dwarfing effect for compounds wherein R 1  and R 2  represent C 5  -C 6  cycloalkyl or 0.28 to 1.2 kg/hectare where R 1  and R 2  are alkyl and have a total of 4 to 5 carbon atoms. 
     Surprisingly, I have also found that certain of the compounds of this invention, particularly those of formula I, wherein X is Cl and R 1  and R 2  each represent alkyl C 1  -C 4 , provided that the sum of the carbon atoms represented by R 1  and R 2  is 5 to 7, or when R 1  and R 2 , taken together with the carbon to which they are attached, represent cycloalkyl C 5  -C 6  ; induce a pronounced increase in relative stem length and/or foliage weight of plants, particularly dicotyledonous plants, when applied at rates of from about 0.25 to 10 pounds per acre or from 0.28 to 11.2 kg/hectare, either to the foliage of plants or to soil containing seeds thereof. These compounds thus find utility as growth enhancing agents for crops, particularly broadleaf crops such as soybeans, cotton, cucumbers and snapbeans. It is, however, also found that these compounds are useful for enhancing the growth rate of sorghum and corn. 
     The plant growth regulating effects of the compounds of the present invention are further demonstrated by the compounds&#39; usefulness for controlling sucker growth on mechanically topped tobacco plants. With the compounds of this invention, it is found that solutions and/or suspensions, preferably aqueous, containing from about 200 to 2000 ppm, and preferably 200 to 1000 ppm, of active compound is effective for inhibiting sucker growth on mechanically topped tobacco plants. 
     In tobacco farming, bud growth is conventionally controlled by two mechanical processing operations. Plant height is regulated by cutting off the terminal bud flower of the tobacco plant in a process known as &#34;topping.&#34; This process facilitates the development of the large leaf which forms the commercial crop. Their development is, however, offset by the enhanced development of lateral (axillary) buds. The lateral growth (called &#34;sucker growth&#34;) again reduces the nutrient supply available for large leaf development. This necessitates a second mechanical operation; namely, the hand removal of the suckers from each tobacco plant. In the practice of the present invention, the inconvenient and expensive mechanical steps can be avoided by two spraying operations. Firstly, terminal bud development can be controlled by an over-spraying of the active ingredient. Secondly, sucker development can be controlled by a subsequent spraying of the plant stem and foliage. 
     Harvesting of the marketable or prime leaves of flue-cured tobacco is usually begun about 1 to 2 weeks after treatment and may continue for 4 or 5 weeks. Usually the leaves are cut from the bottom of the stalk in groups of three at weekly intervals. Inhibiting growth of axillary buds during this period is important since such treatment results in improved quality, texture, and yield of the prime or marketable leaves. Inhibiting growth of axillary buds on topped burley tobacco is also important from the standpoint of improving quality and yield of tobacco, although the harvesting procedure is somewhat different. Accordingly, after the burley tobacco is topped, it is sprayed with a solution of the active material to inhibit axillary bud development, and the whole stalk is then harvested in accordance with standard practices some 5 to 10 weeks after treatment. 
     For use in inhibiting bud growth, the compounds of formula I are used at an application rate of about 1 to 40 mg active compound per plant, preferrably 1 to 20 mg per plant. For this use, X in the formula is preferrably hydrogen, methyl, chloro or methoxy. 
     Inasmuch as the compounds of this invention are only very slightly water soluble, they are generally formulated for foliar treatments as wettable powders or flowable liquids which are usually dispersed in water or other inexpensive liquid diluent for application to said foliage as a liquid spray. However, when said compounds are to be used where soil treatments are involved, the compounds of the invention may also be prepared as granular products. 
     A typical wettable powder can be prepared by grinding together approximately 46% by weight of a finely divided carrier such as attapulgite, 50% by weight of the imidazoisoindoledione or dihydroimidazoisoindoledione of this invention, 3% by weight of the sodium salt of condensed naphthalene sulfonic acids and 1% by weight of sodium N-methyl-N-oleoyltaurate. 
     A typical flowable liquid can be prepared by admixing about 42% by weight of the imidazoisoindoledione or dihydroimidazoisoindoledione, with about 3% by weight of the sodium salt of condensed naphthalene sulfonic acids, 2% by weight of finely divided bentonite and 53% by weight of water. 
     A granular product can be prepared by dissolving the imidazoisoindoledione or dihydroimidazoisoindoledione in methylene chloride and spraying the thus-prepared solution on a granular carrier such as sand, silica, kaolin, corn cob grits, attapulgite, or the like. 
     In accordance with this invention, formula I imidazoisoindolediones can be prepared by cyclization of a phthalimidocarboxamide or a dioxoisoindolineacetamide. Cyclization can be achieved by reacting the said phthalimido derivative or isoindolineacetamide with a strong base, at an elevated temperature in the presence of an organic solvent. 
     The cyclization reaction is preferably conducted at a temperature of from 80° to 150° C in the presence of a base such as sodium or potassium hydroxide, or an acid catalyst such as an aromatic sulfonic acid and a solvent which will azeotrope with water, permitting virtually immediate removal thereof from the reaction mixture as it is formed. 
     Among the solvents which may be employed are toluene, benzene, xylenes and cyclohexane. 
     Bases which may be used include alkali metal hydroxides, alkali metal hydrides, alkali metal oxides, tertiary amines such as diisopropyl ethylamine, 1,5-diazobicyclo[3.4.0]nonene-5; 1,5-diazobicyclo[5.4.0]undecene-5; 1,4-diazobicyclo[2.2.2]octane; tetramethylguanidine, potassium fluoride and quaternary ammonium hydroxides such as trimethylbenzyl ammonium hydroxide and strongly basic ion exchange resins. 
     Acidic reagents which may be employed include aromatic sulfonic acid such as p-toluenesulfonic acid, β-naphthalenesulfonic acid, naphthalenedisulfonic acid, and the like. 
     In many cases, the ring closure may also be achieved by a simple pyrolysis of the phthalimidocarboxamide or dioxoisoindolineacetamide at a temperature between 80° and 250° C. 
     These reactions may be illustrated as follows: ##STR2## 
     It should also be understood that, in the above reaction, when X is not hydrogen the product of the reaction is a mixture of the two isomeric compounds since cyclization occurs at either imide carbonyl group as illustrated below: ##STR3## 
     Furthermore, when R 1  and R 2  represent different groups, the carbon to which R 1  and R 2  are attached is an asymmetric center and the products (as well as their intermediates) exist in d- and l- forms. 
     Formula I imidazoisoindolediones can also be prepared by cyclization of the appropriate alkyl N-(carbamoylalkyl) phthalamate with an alkali metal hydride such as sodium or potassium hydride, in the presence of an inert organic solvent such as toluene, xylene or benzene at an elevated temperature of about 80° to 150° C. This reaction may be illustrated, using NaH as representative of the alkali metal hydride, as follows: ##STR4## wherein X, R 1  and R 2  are as described above. This reaction is especially useful for the preparation of imidazoisoindolediones in which R 1  and R 2  represent bulky groups such as isopropyl or t-butyl groups. 
     Furthermore, as with the previously described method for the preparation of the formula I imidazoisoindolediones, when R 1  and R 2  represent different groups, the carbon atom to which they are attached is an asymmetric carbon atom. Therefore, if one starts with an optically active intermediate such as α-aminocarbonitrile, α-aminocarboxylic acid or α-aminocarboxamide, the intermediate N-(carbamoylalkyl) phthalamate and the imidazoisoindoledione, thus prepared, are optically active. 
     Conversion of the imidazoisoindoledione (I) to the dihydroimidazoisoindoledione (II) is achieved by a reduction reaction. This reaction may be carried out with sodium borohydride or a catalyst such as platinum or palladium catalyst, preferably on a carbon, silica or alumina support. The catalytic reduction is generally conducted under superatmospheric pressure between about 10 psig and 150 psig at an elevated temperature between 80° and 150° C. 
     When R 1  and R 2  represent different groups on the formula II dihydroimidazoisoindolediones, cis and trans isomers (stereoisomers) are obtained and both isomers are found to be biologically active. 
     This reaction may be graphically illustrated as follows: ##STR5## 
     The intermediate phthalimidocarboxamide or dioxoisoindolineacetamide, which is essential to the preparation of the formula I imidazoisoindolediones of the present invention, can be prepared by reacting an appropriate disubstituted ketone with ammonium chloride, sodium cyanide and ammonium hydroxide, to obtain the α,α-disubstituted-α-aminocarbonitrile. This α-aminonitrile is then reacted with phthalic anhydride to give the corresponding phthalamic acid. 
     This reaction is carried out at temperatures from about 20° to 60° C in an inert solvent such as ether, tetrahydrofuran, chloroform, methylene chloride, benzene, toluene and the like. The thus-formed phthalamic acid is then cyclized to the corresponding phthalimidocarbonitrile by heating with a dehydrating agent such as acetic anhydride, acetyl chloride, thionyl chloride, or the like, at temperatures from about 0° to 100° C. Hydration of the thus-formed phthalimidocarbonitrile is preferably carried out with a strong acid such as sulfuric acid, with or without the addition of a non-miscible solvent such as methylene chloride or chloroform and the like at temperatures from about -10° C to +30° C. These reactions are graphically illustrated by using the substituted phthalic anhydride as an example, and including the cyclization of the phthalimidocarboxamide to form the compounds of this invention, as follows: ##STR6## wherein X, R 1  and R 2  are as described above. 
     Alternatively, the above-mentioned intermediate phthalimidocarboxamide may also be prepared by the reaction of phthalic anhydride with a substituted aminocarboxylic acid to obtain the phthalimidocarboxylic acid which is converted to the corresponding acid chloride using thionyl chloride. This reaction is generally conducted in the presence of an inert organic solvent such as toluene, benzene, or the like, at an elevated temperature. The acid chloride is then readily converted to the intermediate phthalimidocarboxamide by reaction with ammonia. This reaction is generally conducted in the presence of a solvent such as tetrahydrofuran at a temperature between about -10° and +15° C. This synthetic route, including the cyclization of the phthalimido carboxamide, is illustrated as follows: ##STR7## wherein X, R 1  and R 2  are as described above. 
     As previously indicated, formula I imidazoisoindolediones can also be prepared by cyclization of an alkyl N-(carbamoylalkyl) phthalamate with an alkali metal hydride. The intermediate α-aminocarboxamide required for the preparation of the alkyl N-(carbamoylalkyl) phthalamate, which is represented by the formula: ##STR8## where R 1  and R 2  are as previously described, can be prepared by reacting an α-aminocarbonitrile with sulfuric acid at an elevated temperature. This carboxamide is then reacted with a 2-carboalkoxybenzoyl chloride to yield the alkyl N-(carbamoylalkyl) phthalamate, referred to above. These reactions may be graphically illustrated as follows: 
    
    
     This invention is further demonstrated by the examples set forth below. 
     EXAMPLE 1 
     Preparation of 3-Isobutyl-3-methyl-5H-imidazo[2,1-a]-isoindole-2(3H),5-dione ##STR10## 
     A solution of 130.1 g (0.5 mole) of α-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetamide in 650 ml toluene is heated with vigorous stirring under a Dean-Stark water separator in order to remove traces of water. The solution was cooled to 100° C and 2.0 g sodium hydroxide in the form of pels is added and the mixture rapidly heated to reflux. Water collects in the water separator. One-half hour after the addition of the sodium hydroxide, a further 2 g is added and heating is continued for a further 11/4 hours when no further water is removed from the reaction mixture and the infrared spectrum of an aliquot indicates the reaction to be complete. The reaction mixture is cooled to room temperature, filtered and the solids washed with toluene and the toluene removed in vacuo to leave a white solid which is transferred to a filter funnel with hexane and air-dried to give 98.7 g. of 2,5-dihydro-3-isopropyl-3-methyl-3H-imidazo[2,1-a]isoindole-2,5-dione, melting point 93°-96° C. The product may be purified by recrystallization from hexane to give an analytically pure sample, melting point 98°-100.5° C. 
     Alternatively, the product may be isolated by adding a slight excess of glacial acetic acid over the amount of sodium hydroxide used to the toluene reaction mixture, adding water, separating the organic phase, washing the organic phase with water, separating the organic phase, drying the organic phase, and finally removing the solvent to yield the product. 
     The above procedure is repeated in all respects, excepting that the strong base reagent is altered. In separate experiments, sodium hydride, potassium hydroxide, barium oxide, diisopropylethylamine, 1,5-diazobicyclo[5.4.0]undicene-5, tetramethylguanidine, tetramethylbenzyl ammonium hydroxide, Amberlite A21 (Rohm &amp; Haas) strongly basic ion exchange resin and p-toluenesulfonic acid, are substituted for sodium hydroxide and yield the desired 3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione. In practice of the above-described method, sodium hydroxide or sodium hydride in refluxing toluene is preferred. 
     Using the procedure described above, but substituting the appropriate phthalimidocarboxamide or dioxoisoindolineacetamide for α-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetamide, and the selected strong base and solvent for sodium hydroxide and toluene, yields the imidazoisoindolinediones reported in Table I below. Table I also indicates the solvent and base used as well as the melting point of the compounds obtained. With regard to the compounds synthesized and reported in Table I, it should be understood that when Y≠H the product is a mixture of two isomeric compounds, since cyclization occurs at both imidecarbonyl groups, for example: ##STR11## 
     In some cases, as shown in Table I, there are separated either by franctional crystallization or column chromatography. In the other cases, the mixture, indicated by a two-number prefix before the substituent X is tested for biological activity. 
     
                                           TABLE I                                 
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 ##STR12##                                                                
Catalyst                          Melting                                 
or                                Point                                   
Base Solvent                                                              
          X     R.sub.1                                                   
                       R.sub.2    ° C                              
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NaH  Toluene                                                              
          H                                                               
                 ##STR13##        133.5-135                               
NaH  Toluene                                                              
          9-Cl  (CH.sub.2).sub.5    251-252                               
NaH  Toluene                                                              
          6-Cl  (CH.sub.2).sub.5  156.5-157.5                             
NaH  Toluene                                                              
          H     CH.sub.3                                                  
                       CH(C.sub.2 H.sub.5).sub.2                          
                                   99-101                                 
NaH  Toluene                                                              
          H     CH.sub.3                                                  
                       CH(CH.sub.3) (C.sub.2 H.sub.5)                     
                                   85.5-87.5                              
NaH  Toluene                                                              
          7/8-CH.sub.3                                                    
                (CH.sub. 2).sub.5   183-187                               
NaH  Toluene                                                              
          H     (CH.sub.2).sub.5    158-162                               
NaH  Toluene                                                              
          6/9-SCH.sub.3                                                   
                (CH.sub.2).sub.5  263.5-264                               
NaH  Toluene                                                              
          6-Cl  CH.sub.3                                                  
                       CH.sub.2 CH(CH.sub.3).sub.2                        
                                    122-124                               
NaH  Toluene                                                              
          9-Cl  CH.sub.3                                                  
                       CH.sub.2 CH(CH.sub.3).sub.2                        
                                    152-154                               
NaH  Toluene                                                              
          H     CH.sub.3                                                  
                       CH.sub.2 CH(CH.sub.3).sub.2                        
                                   98.5-99                                
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     EXAMPLE 2 
     Preparation of 3-tert-Butyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione ##STR14## 
     A suspension of sodium hydride (from 1.92 g of a 50% suspension of sodium hydride in mineral oil) in 150 ml toluene is heated under reflux. During 20 minutes is then added portionwise 6.13 g (0.02 mole) methyl N-(1-carbamoyl-1,2,2-trimethylpropyl)phthalamate to the stirred, refluxing, mixture. Heating is continued for 30 minutes after the addition, the mixture filtered through diatomaceous earth, and the solvent removed in vacuo. The residue crystallizes and is recrystallized from a mixture of acetone-hexane to give 3-t-butyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione, melting point 136.5°-137.5° C. 
     The 3,3-diisopropyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione (melting point 146°-148° C) is prepared in the manner described above, excepting that the methyl ester of N-(1-carbamoyl-1-isopropyl-2-methylpropyl)phthalamic acid is substituted for methyl N-(1-carbamoyl-1,2,2-trimethylpropyl)phthalamate, in the above reaction. 
     EXAMPLE 3 
     Preparation of 1,9b-Dihydro-3-isobutyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione ##STR15## 
     To a stirred suspension of 10.4 g (0.274 mole) sodium borohydride in 164 ml absolute ethanol under nitrogen was added dropwise at 5° C a solution of 133.9 g (0.548 mole) of 2,5-dihydro-3-isopropyl-3-methyl-3H-imidazo[2,1-a]isoindole-2,5-dione in 155 ml tetrahydrofuran. After the addition, the mixture is stirred a further 3 hours at room temperature and then poured over 1070 g ice with stirring. The mixture is acidified with concentrated HCl and after stirring for 1.5 hours, the precipitate removed by filtration, washed with water and air-dried to give 118.7 g of 1,9b-dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione, melting point 178°-200° C. 
     This compound is a mixture of stereoisomers which can be graphically represented as follows: ##STR16## These isomers may be separated by fractional crystallization from acetonitrile to give the less soluble isomer, melting point 234°-236° C and the more soluble isomer, melting point 217°-221° C, which are readily distinguishable by their nmr spectra. It is also understood that each of these stereoisomers exists as a pair of optical isomers by virtue of the asymmetric carbon atom bearing the methyl and isopropyl groups. 
     The reduction can be carried out in lower alkyl alcohols with or without the addition of water at temperatures preferably between 0° to 25° C. Other reducing agents such as sodium cyanoborohydride and lithium borohydride may be used to effect this transformation. 
     The following compounds listed in Table II below are prepared essentially by the procedure described above, but substituting the appropriate imidazoisoindoledione for 3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione, in said procedure. The broad melting points shown in Table II reflect the fact that the compounds are mixtures of cis and trans isomers when R 1  ≠R 2  and that each stereoisomer is a mixture of positional isomers with respect to X when X≠H. 
     
                       TABLE II                                                    
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 ##STR17##                                                                
                                  Melting                                 
                                  Point                                   
X      R.sub.1     R.sub.2        ° C                              
______________________________________                                    
        ##STR18##             252-261                                     
7/8-CH.sub.3                                                              
       (CH.sub.2).sub.5       195-203                                     
H      CH.sub.3    CH(C.sub.2 H.sub.5).sub.2                              
                                  179-185                                 
H      CH.sub.3    CH(CH.sub.3) (C.sub.2 H.sub.5)                         
                                  160-190                                 
H      (CH.sub.2).sub.4        230-232                                    
9-Cl   (CH.sub.2).sub.5       200-201                                     
6-Cl   (CH.sub.2).sub.5                                                   
H      (CH.sub.2).sub.5       238-239.5                                   
6/9-SCH.sub.3                                                             
       (CH.sub.2 ).sub.5      175-185                                     
Cl     CH.sub.3    CH.sub.2 CH(CH.sub.3).sub.2                            
                                   145-195                                
H      CH.sub.3    CH.sub.2 CH (CH.sub.3).sub.2                           
                                  190-209                                 
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     EXAMPLE 4 
     Four-Step Synthesis for the Preparation of Phthalimidocarboxamide Derivatives Essential for the Preparation of Formula I, Imidazoisoindolediones 
     Step 1. Preparation of the α-Aminonitrile 
     The following is a typical procedure: ##STR19## 
     To a mixture containing 79 g (1.477 mole) ammonium chloride and 61.36 g (1.25 mole) sodium cyanide in 400 ml 28% ammonium hydroxide solution is added dropwise with stirring and cooling 86.1 g (1 mole) diethylketone. After stirring overnight, the organic phase is separated and the aqueous phase extracted twice with methylene chloride. The organic phase and extracts are combined, washed with water and dried. The drying agent is removed and the solvent removed in vacuo to leave essentially pure 2-amino-2-ethylbutyronitrile, as shown by the absence of a carbonyl band (1700-1720 cm -1 ) in the infrared spectrum. The aminonitriles can be purified if contaminated with starting ketone by dissolving the crude product in ether, adding anhydrous hydrogen chloride and collecting the precipitated hydrochloride salt. The free aminonitrile can then be regenerated by distributing the salt between methylene chloride and aqueous sodium bicarbonate solution, washing the organic phase with water, drying the organic phase and finally removing the solvent in vacuo. 
     Using this procedure, the following aminonitriles, reported in Table III below, are prepared as oils and characterized only by their infrared spectra. 
     
                       TABLE III                                                   
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 ##STR20##                                                                
R                   R.sub.1                                               
______________________________________                                    
 ##STR21##                                                                
CH.sub.3            C(CH.sub.3).sub.3                                     
CH.sub.3            CH(CH.sub.3)(C.sub.2 H.sub.5)                         
C.sub.2 H.sub.5     C.sub.2 H.sub.5                                       
CH(CH.sub.3).sub.2  CH(CH.sub.3).sub.2                                    
 (CH.sub.2).sub.5                                                         
(CH.sub.2).sub.4                                                          
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     Step 2. Preparation of the Phthalamic Acids 
     The following is a typical procedure: ##STR22## 
     To a stirred boiling mixture of 28.1 g (0.189 mole) of phthalic anhydride in 28 ml methylene chloride is added dropwise 23.6 g (0.21 mole) of 2-amino-2,3-dimethylbutyronitrile in 57 ml methylene chloride. After the addition, heating is continued for 3 hours. The mixture is cooled and the precipitate removed by filtration, washed with methylene chloride and air-dried to give 44.2 g (90%) of N-(1-cyano-1,2-dimethylpropyl)phthalamic acid, melting point 154°-155° C. 
     Other solvents such as ether, tetrahydrofuran, chloroform, benzene and toluene may be used in place of methylene chloride. The reaction can be run at temperatures from 0°-100° C, but preferably at 20°-50° C. 
     The phthalamic acids of Table IV are prepared by the general method described above using the appropriate phthalic anhydride and appropriate aminonitrile. 
     
                       TABLE IV                                                    
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 ##STR23##                                                                
                                 Melting                                  
                                 Point                                    
R.sub.1  R.sub.2          X      ° C                               
______________________________________                                    
 ##STR24##            H      158-162                                      
CH.sub.3 CH(C.sub.2 H.sub.5)(CH.sub.3)                                    
                          H      153.5-154.5                              
CH.sub.3 CH(C.sub.2 H.sub.5).sub.2                                        
                          H      109-113                                  
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     Step 3. Preparation of the Phthalimide Nitriles 
     The following is a typical procedure: ##STR25## 
     A suspension of 26 g (0.1 mole) of N-(1-cyano-1,2-dimethylpropyl)phthalamic acid in 130 ml methylene chloride is heated with stirring under reflux. Thionyl chloride (8.7 ml, 0.12 mole) is added dropwise, and after the addition, the mixture heated for a further 3 hours. A further 5.8 ml (0.08 mole) thionyl chloride is added and heating continued for a further 2.5 hours. The mixture is cooled down, filtered and the solvent removed in vacuo leaving the product as a pale yellow oil which can be crystallized from etherhexane, melting point 48°-51° C. 
     Other solvents such as chloroform, benzene, toluene, ethylene dichloride, and the like, can be used in place of methylene chloride. Other reagents such as acetic anhydride and acetyl chloride may be used in place of thionyl chloride, and the temperature employed can vary from about 10°-130° C. 
     The following Table V lists the phthalimidonitriles prepared by essentially the above procedure. 
     
                       TABLE V                                                     
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 ##STR26##                                                                
                                  Melting                                 
                                  Point                                   
X     R.sub.1    R.sub.2          ° C                              
______________________________________                                    
H     CH.sub.3   CH(C.sub.2 H.sub.5).sub.2                                
                                  oil                                     
H     CH.sub.3   CH(CH.sub.3) (C.sub.2 H.sub.5)                           
                                  oil                                     
       ##STR27##              86-87.5                                     
H     CH.sub.3   CH(C.sub.2 H.sub.5).sub.2                                
                                  --                                      
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     Step 4. Preparation of the Phthalimidocarboxamides 
     The following is a typical procedure: ##STR28## 
     To 404 ml of 85% sulfuric acid is added, with stirring and cooling to maintain a temperature of 14°-16° C, 242.3 g α-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetonitrile in 67 ml methylene chloride. After the addition (2 hours), the cooling bath is removed and the mixture stirred a further 2 hours at room temperature. The reaction mixture is then poured into a stirred mixture of 2 l water and 300 ml toluene. After 1 hour, the crystalline solid is removed by filtration, washed thoroughly with water, suspended in aqueous sodium bicarbonate solution and again filtered. After washing the solid with water, the product, α-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetamide, is air-dried and has melting point 165°-166.5° C. 
     The concentration of the sulfuric acid may be varied from about 70°-100%, and the temperature from about 0°-50° C. Co-solvents such as chloroform, ethylenedichloride, may also be used. 
     The compounds listed in Table VI below are prepared using essentially the same method described above. 
     
                       TABLE VI                                                    
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 ##STR29##                                                                
                                Melting                                   
                                Point                                     
X    R.sub.1      R.sub.2       ° C                                
______________________________________                                    
H    CH.sub.3     CH(CH.sub.3) (C.sub.2 H.sub.5)                          
                                129 - 135                                 
      ##STR30##             204.5 - 205.5                                 
H    CH.sub.3     CH(C.sub.2 H.sub.5).sub.2                               
                                122.5 - 124.5                             
______________________________________                                    
 
    
     EXAMPLE 5 
     Alternate Three-Step Synthesis for the Preparation of Phthalimidocarboxamides Essential for the Preparation of Formula I, Imidazoisoindolediones 
     Step 1. Preparation of the Phthalimidocarboxylic Acids 
     The following procedure is typical: ##STR31## 
     A mixture of 444 g (3 mole) phthalic anhydride, 430 g (3.0 mole) 1-aminocyclohexanecarboxylic acid and 39 ml triethylamine in 4.5 l toluene is heated under reflux with stirring under a Dean-Stark water separator for 21 hours. During this time, 54 ml water is collected. The mixture is slowly cooled to room temperature during which time the product crystallizes from the solution. The product, 1-phthalimidocyclohexanecarboxylic acid, 576.4 g, melting point 176°-178° C, is collected, washed with toluene and air-dried. 
     Other solvents such as acetic acid, benzene, dimethylformamide, xylenes and the like, as well as direct fusion of the two reactants can be used to effect this reaction at temperatures from about 50°-250° C. 
     The following compounds listed in Table VII are prepared by essentially the same procedure using the appropriate amino acid and phthalic anhydride. 
     
                       TABLE VII                                                   
______________________________________                                    
 ##STR32##                                                                
                                 Melting                                  
                                 Point                                    
X       R.sub.1   R.sub.2        ° C                               
______________________________________                                    
H       CH.sub.3  CH.sub.2 CH(CH.sub.3).sub.2                             
                                 133-135                                  
3-Cl    (CH.sub.2).sub.5     193-194                                      
______________________________________                                    
 
    
     Step 2. Preparation of the Phthalimidocarbonyl Chlorides 
     The following procedure is typical: ##STR33## 
     A stirred slurry of 300 g (1.1 mole) 1-phthalimidocyclohexanecarboxylic acid in 2.5 l benzene containing 96 ml (157 g, 1.32 mole) thionyl chloride is heated under reflux for 3.25 hours. The solution is then cooled, filtered and the solvent removed in vacuo to leave the 1-phthalimidocyclohexanecarbonyl chloride as an oil, characterized only by its infrared spectrum and used directly for Step 4, described below. 
     Other solvents such as chloroform, methylene chloride, dichloroethylene, toluene, xylene, and the like, may be used for this reaction at temperatures from about 20°-100° C. Also, other halogenating agents such as thionyl bromide, phosphorus oxychloride may be employed to prepare the reactive acyl halide. 
     The following compounds, listed in Table VIII and characterized only by their infrared spectra, are prepared by essentially the same procedure. 
     
                       TABLE VIII                                                  
______________________________________                                    
 ##STR34##                                                                
X           R.sub.1     R.sub.2                                           
______________________________________                                    
H           CH.sub.3    CH.sub.2 CH(CH.sub.3).sub.2                       
3-Cl        (CH.sub.2).sub.5                                              
______________________________________                                    
 
    
     Step 3. Preparation of the Phthalimidocarboxamides 
     The following is a typical procedure: ##STR35## 
     The crude 1-phthalimidocyclohexanecarbonyl chloride prepared above in Step 3 is dissolved in 3.5 l tetrahydrofuran, and the solution cooled to 5° C. Ammonia is then bubbled into the solution with stirring until infrared analysis of the liquid phase indicates that all the acid chloride is converted to the amide. The reaction mixture is then poured into 8 l of water with stirring, the product removed by filtration, washed with water and air-dried to give 259.1 g of 1-phthalimidocyclohexanecarboxamide, melting point 224°-226° C. 
     Other solvents such as dioxan, toluene and ether may be used instead of tetrahydrofuran at temperatures preferably between 0°-25° C. When water-immiscible solvents are used, the organic phase must be separated, dried and the solvent removed in vacuo and the product crystallized from an appropriate solvent. 
     The compounds listed in the following Table IX are prepared by essentially the same procedure. 
     
                       TABLE IX                                                    
______________________________________                                    
 ##STR36##                                                                
                                  Melting                                 
                                  Point                                   
X       R.sub.1    R.sub.2        ° C                              
______________________________________                                    
H       CH.sub.3   CH.sub.2 CH(CH.sub.3).sub.2                            
                                  170-171                                 
3-Cl    (CH.sub.2).sub.5      193-194                                     
______________________________________                                    
 
    
     EXAMPLE 6 
     Preparation of Phthalamic Acid Esters which are Intermediates for the Preparation of Formula I, Imidazoisoindolediones 
     Step 1. Preparation of α-Aminocarboxamides 
     The following procedure is typical: ##STR37## 
     To 20 g concentrated sulfuric acid at 5° C is added with stirring 10 g of 1-aminocyclohexanecarbonitrile. After the addition, the mixture is heated with stirring at 100° C for 1 hour. The hot solution is then poured onto ice, the solution made strongly basic with 50% aqueous sodium hydroxide solution, and extracted three times with chloroform. The extract is washed with water, saturated NaHCO 3  solution, dried, and the solvent removed in vacuo to leave the product, 1-aminocyclohexanecarboxamide, as a crystalline residue, melting point 99°-102° C. This can be recrystallized from either benzene or ether to give a pure product, melting point 101°-102° C. 
     The α-aminocarboxamides listed in Table X below were prepared by essentially the procedure described above. 
     
                       TABLE X                                                     
______________________________________                                    
 ##STR38##                                                                
                          Melting                                         
                          Point                                           
R.sub.1     R.sub.2       ° C                                      
______________________________________                                    
CH.sub.3    C(CH.sub.3).sub.3                                             
                          185 - 186                                       
______________________________________                                    
 
    
     Step 2. Preparation of the Phthalamic Acid Esters 
     The following is a typical procedure: ##STR39## 
     To a stirred suspension of 16.3 g (0.113 mole) of 2-amino-2,3,3-trimethylbutyramide in 226 ml dry tetrahydrofuran containing 16.4 ml dry triethylamine at 5° C is added dropwise a solution containing 22.4 g (0.133 mole) of 2-carbomethoxybenzoyl chloride [Rec. Trav. Chem. 92, 824 (1973)] dissolved in 56 ml dry tetrahydrofuran. After the addition, the mixture is stirred at room temperature for 2 hours and then poured into 400 ml ice cold water. The product was extracted into ethyl acetate, the extract dried over sodium sulfate, the drying agent removed by filtration, and the solvent removed in vacuo. The residual oil crystallizes and the product, methyl N-(1-carbomoyl-1,2,2-trimethylpropyl)phthalamate, recrystallized from acetone-hexane, melting point 146°-147° C. 
     Other solvents such as ether, dioxane, benzene, toluene, methylene chloride, chloroform, and the like, may be used instead of tetrahydrofuran at temperatures from about 0°-50° C, but preferably at 5°-25° C. 
     EXAMPLE 7 
     Control of Axillary Tobacco Buds 
     Seedling tobacco plants are transplanted into 6-inch plastic pots containing a greenhouse soil mix (loam soil: sand-muck, 1:1:1). The plants are grown in the greenhouse for 8 to 10 weeks and then topped just above the eleventh node. The active ingredients are applied as foliar sprays to the entire plant, immediately after topping. Each spray solution is prepared by dissolving the desired amount of active ingredient in an acetone-water mixture containing 0.5% TWEEN 20, polyoxyethylene sorbitan monolaurate (Atlas Powder Company). The plant to be sprayed is placed on a turntable and 40 ml of the spray solution applied to the plant from three directed nozzles. The concentration of active ingredient in the spray solution is 200 ppm and 1000 ppm. After spraying, the plants are placed at random on a greenhouse bench and watered normally for a period of 2 weeks. At the termination of each test, the suckers are removed from all nodes, weighed and the results expressed as percent inhibition compared with the fresh weight of suckers from untreated controls. The results achieved are set forth in Table XI below. Maleic hydrazide, a commercial bud growth regulant is included for comparison. 
     
                                           TABLE XI                                
__________________________________________________________________________
Tobacco Sucker Inhibition                                                 
                                  Average                                 
                                  Sucker % Sucker                         
                    Fresh Weight of Suckers                               
                                  Weight Inhibition                       
                    Replicate                                             
                           Replicate                                      
                    I      II                                             
                    200 1000                                              
                           200 1000                                       
                                  200 1000                                
                                         200 1000                         
Compound            ppm ppm                                               
                           ppm ppm                                        
                                  ppm ppm                                 
                                         ppm ppm                          
__________________________________________________________________________
Untreated Controls  13.0   39.4   25.8*  --  --                           
                    15.4   28.3                                           
                    21.2   33.7                                           
Maleic Hydrazide    20.4                                                  
                        6.3                                               
                           22.0                                           
                               2.2                                        
                                  21.2                                    
                                      4.2                                 
                                         18   84                          
__________________________________________________________________________
 ##STR40##          2.3 0  5.6 0  2.8 0  89  100                          
__________________________________________________________________________
 *Average Sucker Weight 6 Replications.                                   
 
    
     EXAMPLE 8 
     Plant Growth Regulating Effect of Test Compounds Applied to the Foliage of Plants and to Soil Containing Seeds of Said Plants 
     To evaluate test compounds as plant growth regulating agents, said compounds are dissolved or dispersed in 50/50 aqueous acetone mixtures and applied to the foliage of seedling plants and to seeded pots of test plant species. 
     The plant species used in these tests are as follows: 
     
         ______________________________________                                    
Plant                Variety                                              
______________________________________                                    
Fescue               Kentucky-31                                          
Sorghum              W-55                                                 
Rice                 Nato                                                 
Wheat                Bonanza                                              
Barley               Larker                                               
Corn                 XL-45                                                
Soybean              Adelphia                                             
Cotton               Stoneville                                           
Cucumber             Marketer                                             
Snapbean             Sprite                                               
Peanut               NC-2                                                 
Sugarbeet            Monogerm                                             
______________________________________                                    
 
    
     Treatment consisted of spraying the test compound in acetone:water (1:1) at the rate of 86 gallons per acre with a moving nozzle on a stationary track. The spray nozzle moved at a constant speed over the test species. 
     In soil treatment tests, containers are filled to within 1 inch of the top with greenhouse potting soil, tamped, seeds of test plant species placed on top of the soil, sprayed, then covered with additional potting soil. The pots are watered immediately after treatment and benched at random in the greenhouse. Normal watering and fertilizing practices are followed. Minimum day and night temperatures of 65° F are maintained during cooler portions of the year. Normal daily temperature fluctuations occur during the summer season. 
     Foliage tests are conducted in the same manner described previously in the soil tests. However, the same plant species employed in this test are well established seedlings approximately 2 to 3 inches in height. Plants are watered prior to treatment and are sprayed to provide the same rate of 0.25 and 4 pounds per acre or 0.28 and 4.48 kg per hectare of test compound. 
     Data Recording 
     Initial observations are made at 3 to 5 days after treatment for early germination of test species. Morphological changes from the norm are noted during the test period. Final observations are made 4 weeks after treatment. At this time, measurements of the height of plants are made. From these measurements, increases or decreases as compared to control plants can be noted. Data obtained for both treatments (I = foliar and II = soil) are reported in Tables XII and XIII below. 
     Rating Scale 
     1 No effect 
     2 Poor activity 
     3 Fair activity 
     4 Good activity 
     5 Excellent activity 
     6 Toxic 
     - Inhibition or dwarfing 
     D dead 
     
         TABLE XII
  Observed Plant Growth Enhancement or Dwarfing Rate  kg per Crop Rating
 Hec- FE SOR RI WH BA COR SOY COT CU SN PN SB Compound tare I II I II I
 II I II I II I II I II I II I II I II I II I II
  ##STR41##
  0.281.12 13 13 1 3 11 11 11 12 11 12 12 12 22 35 44 11 11 12 13 -6-6 13 1
1
  11 11 12
  ##STR42##
  0.281.12 34 35 34 11 34 11 34 11 34 23 34 11 45 23 23 12 34 22  34 24
 12 11 23 22
  ##STR43##
  1.124.48 -5-5  1-3 -3-4  1-2  1-6 -6-6 -5-5  1-5 -5-5  1-3  1-6 11 -6-6 1
6
  11 11 -6-6  1-2 -6-6 16 11 11 -6-6  1-5
  ##STR44##
  1.124.48  1-4 -2-3  1-6  1-6 11  1-6  1-5 -2-5  1-5  1-2  1-6  1-2  1-5 1
2
  11 11 -6-6 11  1-5 12 11 11  1-2  1-2
  ##STR45##
  1.124.48 -4-5 -3 -5  1-4  1-6 11 -6-6  1-2  1-3  1-5  1-3  1-4  1-3
 2-4  1-2 11 11  1-6  1-6  2-4  1-2 11 11  1-6  1-5  and
  ##STR46##
  ##STR47##
  1.124.48 11  1-2 11 11 11 11 11  1-5 11  1-4 11 11 12  1-2 11  1-3 11
 1-4 11  1-3 11 11 11  1-2  and
  ##STR48##
  ##STR49##
  0.281.12 4.48 -5-5-6 -5-6-6 -6-6-6 -6-6-6  1-6-6 -6-6 0 -4-5-6 -5-5-6
 -6-6-6 -6-6-6 -6-6-6 -6-6-6 -6-6-6  1-5-5  1-6-6  1-6-6 -6-6-6 -6-6-6    6
 -6--6 -6-6-6 -3-5-5 -3-5-6  -6-6-6 -5-6-6
 I = Foliar Treatment
 II = Soil Treatment
 FE = Fescue
 SOR = Sorghum
 RI = Rice
 WH = Wheat
 BA = Barley
 COR = Corn
 SOY = Soybean
 COT = Cotton
 CU = Cucumber
 SN = Snapbean
 PN = Peanut
 SB = Sugar beet
 
    
     
         TABLE XIII
  Measurement of Plant Growth Enhancement or Dwarfing Rate kg Plant
 Weight in Grams per FE SOR RI WH BA COR SOY COT CU SN PN SB Compound
 Hectare I II I II I II I II I II I II I II I II I II I II I II I
 II
  ##STR50##
  0.281.12 3828 4028 6878 66 63 2427 3337 3128 3434 4844 4447 8790 7168   6
 538 3833 4043 3936 3833 4351 3134 3442 3637 2733 D19 1616
  ##STR51##
  0.281.12 2533 3231 7173 5860 3128 4042 2526 3635 3241 4545 9082 7162
 5755 3736 3337 3233 6243 4340 3637 3532 4128 3427 1016 1516
  ##STR52##
   1.124.48 2123 2933 5032 6160 2218 3221 1817 3635 2816 4247 8080 6061   1
 263 4038 3836 3231 3218 3938 2513 3024 3637 2125 DD 1416
  ##STR53##
  4.48 21 25 30 60 16 21 20 25 29 48 79 60 26 31 39 28 20 31 21 17 33 29
 D
  7
 ##STR54##
  4.48 15 20 61 30 23  5 22 30 36 24 73 72 38 32 34 27 18 28 26 23 31 25
 D
  5 and
 ##STR55##
  ##STR56##
  0.281.12 2215 263 24D 593 2313 1922 28D 2720 24D 4224 28D 545 2218 2814
 3441 3022 1514 114 11O 107 2826 2420 DD 5D
  ##STR57##
  4.48 23 25 69 57 28 25 26 24 44 35 96 60 53 26 38 18 42 27 29 25 34 22
 20 16 and
  ##STR58##
  Untreated Controls -- 28 27 72 63 24 31 27 33 41 42 92 68 56 33 40 28
 52 26 30 25 41 28 14 15 &#34; -- 28 24 69 62 31 26 21 36 43 48 86 69 46 36
 36 32 61 31 21 28 30 28 13 17 &#34;-- 23 28 75 60 32 34 24 36 42 45 74 65 42
 30 28 27 37 2728 26 30 27 16 17 &#34;-- 33 21 68 58 35 27 29 33 40 51 69 64
 50 37 34 34 50 36 23 21 32 28 10 17 &#34; -- 34 24 65 60 28 27 29 33 49 43
 90 66 50 35 36 32 50 36 21 28 38 33 11 14 Average of Untreated Controls
 -- 29 25 70 61 30 29 26 34 43 46 82 66 49 34 35 31 50 31 25 26 34 29 13
 16
  I = Foliar Treatment
 II = Soil Treatment
 FE = Feacue
 SOR = Sorghum
 RI = Rice
 WH = Wheat
 BA = Barley
 COR = Corn
 SOY = Soybean
 COT = Cotton
 CU = Cucumber
 SN = Snapbean
 PN = Peanut
 SB = Sugar beet
 
    
     EXAMPLE 9 
     Evaluation of Test Compounds as Plant Growth Regulating Agents 
     In these tests, containers are prepared by putting 100 ml of soil (soil type described previously) in each 23/4 inch square plastic pot as a base, then three Amsoy soybean seeds are placed on this base and are covered with soil (3/8 to 1/2 inch). Seeds of Kentucky 31 Fescue are separately mixed with soil and 50 ml of the soil-seed mix are added to the pot to provide each pot with approximately 625 fescue seeds. 
     To prepare the test compounds, 20 mg of the compound is placed into a two-ounce, wide-mouth glass bottle and dissolved or dispersed in a 50/50 acetone/water mixture sufficient to prepare a 1000 ppm solution or suspension. 
     An addition of 5 ml of the 1000 ppm solution in each cup is equivalent to 10 lbs/acre or 11.2 kg/hectare. 
     Just prior to the application of the compounds, the test pots are tamped to level the soil and are lightly watered to prevent formation of air pockets and channelling routes during application which would prevent even distribution of the test compound in the soil with a pipettor. Three replications are used for each compound. 
     Each test includes 5 ml of 1:1 acetone:water controls, 5 ml water controls as a standard for comparison of activity from test to test. The treated plants are benched in the greenhouse and normal watering practices are followed. Minimum day and night temperatures of 65° F are maintained during cooler portions of the year. Normal daily temperature fluctuations occur during the summer season. Data obtained are reported below in Table XIV. 
     Data Recording 
     Initial observations are made at 3 to 5 days after treatment for early germination of both test species. Physiological or morphological changes from the norm are noted during the test period. Final observations are made at 2 to 3 weeks after treatment (dependent on time of year). At this time, measurements of the height of plants of both species are made. From these measurements, percent increases or decreases as compared to control plants, are calculated. 
     From the data reported below, it can be seen that all compounds tested increased the height of soybean plants; that with the exception of 7&#39;(and 8&#39;)-methyl-spiro{cyclohexane-1,3&#39;-(3H)imidazo[2,1-a]isoindole}-2&#39;,5&#39;-dione; 9&#39;-chloro-1&#39;,9&#39;b-dihydro-spiro{cyclohexane-1,3&#39;-(3H)imidazo[2,1-a]isoindole}-2&#39;,5&#39;-dione; and 9(or 6)-chloro-3-isobutyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione, all showed an increase in soybean plant weight; that 9&#39;-chloro-spiro{cyclohexane-1,3&#39;-(3H)imidazo[2,1-a]isoindole}-2&#39;,5&#39;-dione; 9(or 6)-chloro-3-isobutyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione and 9&#39;-chloro-1&#39;,9&#39;b-dihydro-spiro{cyclohexane-1,3&#39;-(3H)imidazo[2,1-a]isoindole}-2&#39;,5&#39;-dione, caused a pronounced increase in fescue weight and a weight increase, and that the 7&#39;(and 8&#39;)-methyl-spiro{cyclohexane-1,3&#39;-(3H)imidazo[2,1-a]isoindole] -2&#39;,5&#39;-dione and 3-isobutyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione caused pronounced dwarfing of the fescue. 
     
                       TABLE XIV                                                   
______________________________________                                    
Plant Growth Regulating Effect of Test Compounds                          
on Soybeans and Fescue                                                    
              Soybean    Fescue                                           
                Height  Weight   Height                                   
                                       Weight                             
Compound        (cm)    (g)      (cm)  (g)                                
______________________________________                                    
Untreated Controls                                                        
                14.5     6.31    14.0   4.47                              
Average of Ten                                                            
Replicates                                                                
9&#39;-Chloro-spiro{cyclo-                                                    
                25.0    7.2      24.0  6.1                                
hexane-1,3&#39;-(3H)-                                                         
                30.0    6.3      24.0  5.6                                
imidazo[2,1-a]iso-                                                        
                23.0    7.6      26.0  5.0                                
indole}-2&#39;,5&#39;-dione                                                       
9&#39;-Chloro-1&#39;,9&#39;b-                                                         
                16.0    5.5      22.0  4.9                                
dihydro-spiro{cyclo-                                                      
                17.0    6.8      22.0  5.2                                
hexane-1,3-40 -(3H)-                                                      
                15.0    6.0      24.0  4.8                                
imidazol[2,1-a]iso-                                                       
indole}-2&#39;,5&#39;-dione                                                       
7&#39;(and 8&#39;)- ethyl-                                                        
                19.0    4.6      10.0  1.4                                
spiro{cyclohexane-                                                        
                14.0    --        8.0  0.9                                
1,3&#39;-(3H)imidazo-                                                         
                14.0    --        9.0  1.2                                
[2,1-a]isoindole}-                                                        
2&#39;,5&#39;-dione                                                               
3-Isobutyl-3-methyl-                                                      
                16.0    6.1      12.0  3.5                                
5H-imidazo[2,1-a]-                                                        
                14.0    7.4      10.0  5.2                                
isoindole-2(3H),5-                                                        
                16.0    6.9      14.0  3.8                                
dione                                                                     
6&#39;(and 9&#39;)-Methyl-                                                        
                15.0    6.5      14.0  3.7                                
thio)-spiro{cyclo-                                                        
                18.0    6.8      12.0  2.8                                
hexane-1,3&#39;-(3H)-                                                         
                16.0    7.2      14.0  2.9                                
imidazo[2,1-a]-                                                           
isoindole}-2&#39;,5&#39;-                                                         
dione                                                                     
6&#39;(or 9&#39;)-Chloro-                                                         
                15.0    6.6      15.0  3.8                                
spiro{cyclopentane-                                                       
                15.0    6.5      14.0  4.1                                
1,3&#39;-(3H)imidazo-                                                         
                17.0    6.4      16.0  2.7                                
[2,1-a]isoindole}-                                                        
2&#39;,5&#39;-dione                                                               
6(or 9)-Chloro-3-                                                         
                15.0    6.6      16.0  4.5                                
isobutyl-3-methyl-                                                        
                18.0    7.4      17.0  3.9                                
5H-imidazo[2,1-a]-                                                        
                14.0    6.5      19.0  3.8                                
isoindole-2-(3H),5-                                                       
dione, (isomer 1)                                                         
9(or 6)-Chloro-3-                                                         
                17.0    5.5      18.0  5.4                                
isobutyl-3-methyl-                                                        
                17.0    6.3      18.0  5.9                                
5H-imidazo[2,1-a]-                                                        
                17.0    6.2      18.0  4.9                                
isoindolc-2(3H),5-                                                        
dione, (isomer 2)                                                         
______________________________________                                    
 
    
     EXAMPLE 10 
     Tobacco Bud Inhibition 
     In the following tests Xanthia tobacco growing in 15 cm pots were topped. Three days after topping, when buds had formed and were 1 to 1.5 cm in length, the tobacco plants were sprayed with 40 ml of a 50/50 acetone/water solution containing 1 mg to 40 mg of test compound and 0.1% of a spreader-sticker, the principal functioning agents of which are alkylarylpolyethoxy ethanol, free and combined fatty acids, glycol ethers (dialkyl); benzenedicarboxylate and isopropanol, marketed by Colloidal Products Corporation, Sausalito, California, under the tradename Colloidal BIO-FILM®. 
     Untreated plants were used as controls. 
     Three weeks after spraying the plants were harvested and the fresh weight of the suckers determined. Five plants per treatment were used and the results averaged for all five plants in each treatment. 
     Data obtained are reported in Table XV below. 
     
                       Table XV                                                    
______________________________________                                    
Tobacco Bud Growth Inhibition                                             
                           Avg                                            
                   Rate    Fresh wt %                                     
                   mg/     of Suck- Sucker                                
Compound           plant   ers gm   Control                               
______________________________________                                    
Untreated Controls --      30.8     --                                    
Spiro[Cyclopentane-1,3&#39;-[3H]                                              
                   8       28.2     8.4                                   
imidazo[2,1-a]isoindole)1-2&#39;,                                             
                   40      6.4      79.2                                  
5&#39;-dione                                                                  
Untreated Controls --      29.9     --                                    
Spiro[(Cyclohexane-1,3&#39;-[3-H]                                             
                   8       9.6      67.9                                  
imidazo[2,1-a]isoindole)]-2,                                              
                   40*     0.9      97.0                                  
5-dione                                                                   
3-Methyl-3-phenyl-5-Himidazo                                              
                   8       20.1     2.7                                   
[2,1-a]isoindole2(3H), 5-dione                                            
                   40      25.9     13.4                                  
3-Methyl-3-vinyl-5-Himidazo                                               
                   8       23.8     20.4                                  
[2,1-a]isoindole-2-(3H), 5                                                
                   40      23.3     22.1                                  
dione                                                                     
3-[Isopropyl-3-methyl-5H- 8                                               
                   0.5     98.3                                           
imidazo[2,1-a]isoindole 2                                                 
                   40*     0.4      98.7                                  
(3H)-5-dione                                                              
Untreated Controls --      36.4     --                                    
3,7(and 3,8)-Dimethyl-3-isopro-                                           
                   4       3.7      89.8                                  
pyl-5H-imidazo[2,1-a]isoin-                                               
                   20*     0.3      99.1                                  
dole 2(3H), 5-dione                                                       
Untreated Controls --      34.1     --                                    
3-Isopropyl-3-methyl-5H-                                                  
                   1       9.8      71.3                                  
imidazo[2,1-a]isoindole-2(3H)                                             
                   3       0.9      97.4                                  
5-dione            6*      0.3      99.1                                  
Untreated Controls --      28.9     --                                    
7(and 8)Chloro-3-isopropyl-3-                                             
                   4       16.2     43.9                                  
methyl-5H-imidazo[2,1-a]                                                  
                   20      6.2      78.5                                  
isoindole-2(3H)5-dione                                                    
7(and 8)-Methoxy-3-methyl-3H                                              
                   4*      10.7     63                                    
imidazo[2,1-a]isoindole-2(3H),                                            
5-dione                                                                   
______________________________________                                    
 * =  Slight frenching and/or stem injury