Aminoguanidine compounds, their compositions and pharmaceutical uses
This application is a continuation of application Ser. No. 680,915, filed on Dec. 12, 1984. 
    
    
     The invention relates to new aminoguanidine derivatives of the formula (I), ##STR2## wherein 
     R 1 , R 2  and R 3  each represent hydrogen or halogen atom, C 1-4  alkyl, nitro, trifluoromethyl or C 1-4  alkoxy group, 
     R 4  and R 5  represent a C 1-4  alkyl group, furthermore NR 4  R 5  may form a 5 to 7 membered saturated heterocyclic group containing either one or two nitrogen atoms or a nitrogen and an oxygen atom and being optionally substituted by one or two methyl, hydroxymethyl or hydroxyethyl groups, 
     R 6  and R 7  each represent atom, normal or branched C 1-4  alkyl or C 2-4  alkenyl group, 
     and to their pharmaceutically acceptable acid addition salts as well as to a process for the preparation thereof. 
     Several aminoguanidine derivatives are described in the literature. The 1-aryloxy-alkyl-aminoguanidine derivatives are adrenergic neuron blocking agents (J. Med. Chem. 10, 391/1967/), the 1,1-dialkyl-aminoguanidine derivatives are pesticides (published South African patent application No. 69 03,667), while the 1-phenyl-alkyl-aminoguanidines (Neth. patent application No. 6,505,684 and J. Med. Chem. 13, 1051/1970/), 4-phenyl-aminoguanidines (published German patent application No. 2,452,691 and U.S. Pat. No. 4,101,675) and 1-phenyl-4-monoalkyl-aminoguanidines (published South African patent application No. 69 04,823) are antihypertensive agents. 
     The new compounds of formula (I) of the invention--the 1-phenyl-4,4-disubstituted-aminoguanidine derivatives--are different in structure from the known 1-phenyl-aminoguanidine derivatives, and affect favourably the rhythmic disorders of the heart, i.e. they are potent antiarrhythmic agents. 
     The compounds of formula (I) are prepared according to the invention either by 
     a. reacting a phenylhydrazine derivative of formula (II) ##STR3## wherein R 1 , R 2 , R 3  and R 7  are defined as above, or its acid addition salt, with either an N,N-disubstituted-cyanamide of formula (III), ##STR4## wherein R 4 , R 5  or NR 4  R 5  are as defined above, or with an isothiourea derivative of formula (IV), ##STR5## wherein R 4 , R 5  or NR 4  R 5  and R 6  are as defined above or with its acid addition salt; or 
     b. reacting an isothiosemicarbazide derivative of formula (V), ##STR6## wherein R 1 , R 2 , R 3 , R 6  and R 7  are as defined above or its acid addition salt, with a secondary amine of formula (VI), ##STR7## wherein R 4 , R 5  or NR 4  R 5  are as defined above, or with its acid addition salt, and, if desired, the free base of the formula (I) is liberated from its salt and/or is converted into its acid addition salt by a pharmaceutically acceptable acid. 
     The tautomers of the above compounds as well as mixtures thereof prepared either by method a. or b. are within the scope of the invention. 
     According to a preferred variant of method a. of the invention 1.0M of the phenylhydrazine derivative of formula (II) or its salt, preferably its hydrohalogenide, is reacted with 1.1 to 1.25M of the cyanamide derivative of formula (III), or with 1.0M of the isothiourea derivative of formula (IV) or its salt, preferably its hydrohalogenide, in an inert solvent, in a temperature range of 80° to 160° C., preferably at 90° to 130° C., under nitrogen gas. Cyclohexanol, or C 2-6  normal or branched aliphatic alcohols, i.e. ethanol, n-propanol, i-propanol, n-butanol, amylalcohol or hexylalcohol, are preferred solvents for the reaction. Depending on the solvent and temperature applied the reaction time may amount to 3-72 hours. 
     According to an other variant of method a. of the invention the starting materials are melted under nitrogen, preferably at 100° to 130° C. In the reaction of the compounds of formula (II) and (IV) the starting materials are cautiously melted at 110° C. under nitrogen flow, and the melted mixture is stirred for several hours at 130° C. As during the condensation reaction methylmercaptan gas is formed, the end of the reaction can be recognised by the end of gas formation. In the reaction of the compounds of formulas (II) and (III) the progress of the reaction can be monitored by thin-layer chromatography. 
     According to the preferred method b. of the invention 1M of the thiosemicarbazide salt of formula (V), preferably its hydrobromide or hydroiodide, is reacted with 1M of a secondary amine of formula (VI), or 1M of the thiosemicarbazide of formula (V) is reacted with a salt of the secondary amine of formula (VI), preferably its hydrochloride, either in the presence or the absence of a solvent, in a temperature range of 20° to 130° C., for 3 to 72 hours. The solvents applied in variant a. of the process can preferably be used. The reaction temperature of the reaction in melt, performed in the absence of any solvent, is preferably 110° to 130° C. The end of the reaction can be recognized by the end of methylmercaptan gas formation. 
     In the reaction, performed in a solvent according to either of the process variants, the product formed is precipitating in most of the cases from the reaction mixture upon cooling, and can be separated by filtration. In those cases where the product formed fails to precipitate from the solution upon cooling, its precipitation can be induced by the addition of hexane, ether or acetone. In the reactions carried out in melt the cooled melt is dissolved in ethanol, the insoluble part is filtered, and the product is precipitated from the filtrate by the addition of hexane, ether or acetone. The raw product is purified similarly. 
     If the acid addition salt of the starting material is applied, in the reaction the acid addition salt of the target product is formed. The base can be set free therefrom with an inorganic or organic base, preferably with solid sodium hydrocarbonate or aqueous triethylamine. If desired, the base can be converted into various other acid addition salts with a suitable organic or inorganic acid. 
     The starting materials of general formulas (II), (III), (IV), (V) and (VI) as well as the processes for their preparation are known from the literature [J. Am. Chem. Soc. 81, 4678 (1959); American Chem. J. 42, 23, Zeitschrift fur Elektrochemie 22, 342; J. Am. Chem. Soc. 72, 4699 (1950)]. 
     In the process of the invention the following starting phenylhydrazines of general formula (II) or their salts are preferably used: phenylhydrazine, 2-methyl-, 4-methyl-, 2-chloro-, 3-chloro-, 4-chloro-, 2-trifluoromethyl-, 3-trifluoromethyl-, 2-methoxy-, 2,3-dimethyl-, 2,4-dimethyl-, 2,5-dimethyl-, 2,6-dimethyl-, 2-methyl-6-ethyl-, 2,4,6-trimethyl-, 2-methyl-3-chloro-, 2-methyl-4-chloro-, 2-methyl-6-chloro-, 2,5-dichloro-, 2,6-dichloro-, 2-methoxy-, 3,4-dimethoxy-, and 4-nitro-phenylhydrazine as well as α-methyl-, α-i-propyl- and α-allyl-phenylhydrazine. 
     In the process of the invention the following N,N-disubstituted-cyanamides of formula (III) are preferably applied as starting materials: dimethyl-cyanamide, diethyl-cyanamide, 1-cyano-pyrrolidine, 1-cyano-piperidine, 1-cyano-2-methyl-, 1-cyano-3-methyl-piperidine, 4-cyano-1-methyl-, 4-cyano-2,6-dimethyl-, 4-cyano-1-(2-hydroxyethyl)-piperazine, 4-cyano-, 4-cyano-2-methyl-, 4-cyano-2,6-dimethylmorpholine and 1-cyano-hexahydro-azepine. 
     The following S-methyl-isothioureas of formula (IV) and their salts can preferably be used as starting materials: N,N,S-trimethyl-isothiourea, N,N-diethyl-S-methyl-isothiourea, N,N-tetramethylene-S-methylisothiourea, N,N-pentamethylene-S-methyl-isothiourea, N,N,N&#39;,S-tetramethyl-isothiourea and N,N-diethyl-N&#39;,S-dimethyl-isothiourea. 
     The following isothiosemicarbazide derivatives of formula (V) and their salts can preferably be used as starting materials: 2-methyl-phenyl-S-methyl-, 2-chloro-phenyl-S-methyl-, 3-chloro-phenyl-S-methyl-, 2,6-dichloro-phenyl-S-methyl-, 2,6-dimethyl-phenyl-S-methyl-, 2-methyl-phenyl-N,S-dimethyl-, 2-chloro-phenyl-N,S-dimethyl-, 2,6-dimethyl-phenyl-N,S-dimethyl-, 2,6-dichloro-phenyl-N,S-dimethyl-isothiosemicarbazide. 
     The following secondary amines of formula (VI) and their salts can preferably be used as starting materials: dimethylamine, diethylamine, pyrrolidine, piperidine, 2-methyl-, 3-methyl-piperidine, N-methyl-, 2,6-dimethyl-, N-(2-hydroxyethyl)-piperazine, morpholine, 2-methyl-, 2,6-dimethyl-morpholine, hexamethyleneimine. 
     The 1-phenyl-aminoguanidine derivatives of formula (I) exhibit high antiarrhythmic activity in mouse, cat, guinea pig and dog. In several tests, in doses of 10-50-100 mg/kg, this antiarrhythmic effect is significant and stable both at parenteral and oral administration. 
     The antiarrhythmic activity was tested by the following methods: 
     1. Aconitin-induced arrhythmia in mice 
     Arrhytmia was induced in male mice, weighing 20 to 25 g, by treating them continuously, at a rate of 0.2 ml/min with an infusion containing 5 μg/kg of aconitin. The test compound was administered to the animals either intraperitoneally (by injecting it into the abdominal cavity) 15 minutes before the start of the infusion, or orally 60 minutes before the onset of the infusion. The time of the appearance of arrhythmia was recorded, and the percentage of delay was calculated in relation to the data obtained in the controls, pretreated with 0.9 percent sodium chloride solution only [B. Vargaftig and J. L. Coignet: European J. of Pharmacol. 6, 49 to 55 (1969); N. K. Dadkar and B. K. Bhattachariya: Arch. Int. Pharmacodyn. 212, 297 to 301 (1974); D. U. Nwagwu, T. L. Holcslaw and S. J. Stohs: Arch. Int. Pharmacodyn. 229, 219 to 226 (1977)]. 
     The results are presented in Tables 1 and 2. 1-(2,6-Dimethylphenoxy)-2-aminopropane hydrochloride (Mexiletin) and/or quinidine were applied as reference substances. The actute toxicity values (LD 50 ) were calculated according to the method of Litchfield and Wilcoxon [J. Pharmacol. Exp. Ther., 96, 99 to 113 (1949)]. 
     
                       TABLE 1                                                     
______________________________________                                    
Examination of the antiarrhythmic effect in anesthesized                  
mice treated with aconitin, with intraperitoneal administration           
of the test compounds                                                     
                  Delay in the                                            
                  appearance                                              
Compound Dose     time of    Number of                                    
                                      LD.sub.50                           
Example  mg/kg    arrhythmia animals  mg/kg                               
No.      i.p.     %          n        i.p.                                
______________________________________                                    
1        25       +164       18       81                                  
         50       +174       18                                           
2        25       +79        16       73                                  
         50       +156       16                                           
3        10       +108       12                                           
         20       +68*       12                                           
4         5       +28         5                                           
         10       +77*        9                                           
5        25       +113       20       130                                 
         50       +155       20                                           
6        50       +114        6                                           
7        25       +50        10                                           
         50       +128       20                                           
8         5       +32         6                                           
         10        +110*      7                                           
9        50       +171       12                                           
15       50       +67         6                                           
21       25       +110        6                                           
         50        +86**      9                                           
22       50       +100       20                                           
Reference                                                                 
          5       +3.5       20       114                                 
substance:                                                                
         10       +7.7       20                                           
1-(2,6-di-                                                                
         25       +33        20                                           
methyl-  50       +83        20                                           
phenoxy)-                                                                 
         75       +162       16                                           
2-amino-                                                                  
propane                                                                   
HCl                                                                       
(Mexiletin)                                                               
______________________________________                                    
 *compound is toxic in higher doses                                       
 **compound is toxic in higher doses and induces bradycardia              
 
    
     
                       TABLE 2                                                     
______________________________________                                    
Examination of the antiarrhythmic effect in anesthesized                  
mice treated with aconitin, with oral administration of                   
the test compounds                                                        
                  Delay in the                                            
                  appearance                                              
Compound Dose     time of    Number of                                    
                                      LD.sub.50                           
Example  mg/kg    arrhythmia animals  mg/kg                               
No.      p.o.     %          n        p.o.                                
______________________________________                                    
1         50      +102       5        203                                 
         100      +197       14                                           
2         25      +39        15       220                                 
          50      +71        5                                            
         100      +150       5                                            
5        100      +111       20       400                                 
6        100      +70        6                                            
7         50      +54        6                                            
         100      +137       8                                            
18       100      +74        6                                            
Reference                                                                 
         100      +93        20       390                                 
substance:                                                                
Mexiletin                                                                 
______________________________________                                    
 
    
     2. Determination of the fibrillation threshold in anaesthesized cats 
     The chests of the cats were opened under chloralose-urethane anaesthesia, a bipolar stimulating electrode was fixed onto the heart, and the heart was stimulated electrically with a frequency of 20 Hz, under continuously increasing current strength, until a fibrillo-flattern could be observed. This current strength was considered as the fibrillation threshold of the animal. Thereafter the test compounds were administered, and the increase in the fibrillation threshold value was recorded at i.v. and intraduodenal (i.d.) administration (Szekeres and Papp: Experimental Cardiac Arrhythmias and Antiarrhythmic Drugs, Academic Press, Budapest, 1971). 
     The values are presented in Tables 3 and 4. 
     
                       TABLE 3                                                     
______________________________________                                    
Effect of the test compounds on the fibrillation threshold                
measured in anaesthesized cat at i.v. administration                      
                 Percentual change in the fibrillation                    
Compound                                                                  
        Dose     threshold                                                
Example mg/kg    2 min     10 min   20 min                                
No.     i.v.     following treatment                                      
______________________________________                                    
5       0.5      +18.75    +40.75   +37.6                                 
        1.0      +35.2     +55.2    +48.4                                 
        2.0      +101.1    +93.0    +94.15                                
        4.0      +153.3     +125.65 +124.0                                
        8.0      +392.8    +354.5    +310.25                              
11      2.0      +130.6    +149.0   +163.3                                
        4.0      +176.0    +328.0   +316.0                                
Mexiletin                                                                 
        10.0     --        +161.2   +92.0                                 
______________________________________                                    
 
    
     
                                           TABLE 4                                 
__________________________________________________________________________
Effect of the test compounds on the fibrillation threshold measured in    
anaesthesized                                                             
cats at i.d. administration                                               
Compound                                                                  
      Dose                                                                
          No. of                                                          
              Percentual change in the fibrillation threshold             
Example                                                                   
      mg/kg                                                               
          animals                                                         
              10  20  30  40  50  60  70  80  90  100                     
No.   i.d.                                                                
          n   minutes following treatment                                 
__________________________________________________________________________
 5    20  7   +22.2                                                       
                  +29.0                                                   
                      +94.0                                               
                          +103.7                                          
                              +100.4                                      
                                  +105.8                                  
                                      +100.3                              
                                          +121.5                          
                                              +132.8                      
                                                  +132.3                  
11    20  4   +5.8                                                        
                  +22.0                                                   
                      +43.8                                               
                          +79.6                                           
                              +115                                        
                                  +118                                    
                                      +141                                
                                          +198                            
                                              +209.5                      
                                                  +272.5                  
Quinidine                                                                 
      10  5   +0.4                                                        
                  +26.7                                                   
                      +58.5                                               
                          +48.5                                           
                              +32.1                                       
                                  +20.8                                   
                                      +9.5                                
                                          +8.8                            
                                              +3.8                        
                                                  0.0                     
__________________________________________________________________________
 
    
     3. Electrophysiological tests performed in the isolated rabbit heart 
     Hearts of rabbits of both sexes, weighing 1 to 2 kg, were removed, the right and left auricles and a segment of the right ventricle were prepared and placed into a vessel filled with nutrient solution. Bipolar platinum electrodes (a stimulating electrode and a lead electrode) were placed on the organ strips, and the electric stimulus threshold and the speed of impulse conduction were measured. The effective refractory period was determined on the basis of the maximal driving frequency. The results were read from the screen of an oscilloscope (Szekeres and Papp: Experimental Cardiac Arrhythmias, Academic Press, Budapest, 1971). 
     The electrophysiological activities of the compounds of the invention are demonstrated on the example of 1-(2-methylphenyl)-4,4-dimethyl-aminoguanidine hydrochloride (Example 1). The test results are presented in Table 5. 
     The Table shows that the conduction time in both the left auricle and the right ventricle is prolonged dose-dependently by the compound of the invention, which means a reduction of the speed of impulse conduction. It decreases the maximal driving frequency, indicating a prolongation of the refractory period. The auricular contractility is dose dependently, though moderately reduced by the compound. 
     
                                           TABLE 5                                 
__________________________________________________________________________
Electrophysiological effect in the isolated rabbit heart                  
      Compound                                                            
Test  Example                                                             
parameters                                                                
      No.   0.25 mg/l                                                     
                 0.5 mg/l                                                 
                      1.0 mg/l                                            
                           2.0 mg/l                                       
                                4.0 mg/l                                  
                                     8.0 mg/l                             
__________________________________________________________________________
            Percentual dose responses measured in the right ventricle n = 
            4                                                             
Change in                                                                 
      1     +0.2 +3.31                                                    
                      +14.84                                              
                           +36.75                                         
                                +52.45                                    
                                     +77.82                               
conduction                                                                
      Mexiletin            +11                                            
time                                                                      
Change in                                                                 
      1     0    -1.43                                                    
                      +5.42                                               
                           +20.6                                          
                                +23.6                                     
                                     +35.8                                
electric                                                                  
      Mexiletin            +6                                             
stimulus                                                                  
threshold                                                                 
Change in                                                                 
      1     -0.88                                                         
                 -0.38                                                    
                      -1.82                                               
                           -10.33                                         
                                -17.43                                    
                                     -36.8                                
max. driv-                                                                
      Mexiletin            -28                                            
ing                                                                       
frequency                                                                 
            Percentual dose responses measured in the left auricle n = 4  
Change in                                                                 
      1     +0.54                                                         
                 +8.66                                                    
                      +12.55                                              
                           +28.42                                         
                                +47.87                                    
                                     +114.03                              
conduction                                                                
      Mexiletin            +24                                            
time                                                                      
Change in                                                                 
      1     0    -1.82                                                    
                      -11.8                                               
                           +30.84                                         
                                +43.4                                     
                                     +83.9                                
electric                                                                  
      Mexiletin            36                                             
stimulus                                                                  
threshold                                                                 
Change in                                                                 
      1     -0.08                                                         
                 -0.98                                                    
                      -9.21                                               
                           -17.09                                         
                                -28.82                                    
                                     -59.1                                
max. driv-                                                                
      Mexiletin            -32                                            
ing                                                                       
frequency                                                                 
Contrac-                                                                  
      1     -2.61                                                         
                 -7.57                                                    
                      -15.5                                               
                           -18.12                                         
                                -27.08                                    
                                     -37.92                               
tility                                                                    
__________________________________________________________________________
 
    
     It appears from the above tables that the compounds of the invention are similar or occasionally even superior in antiarrhythmic activity to the presently applied 1-(2,6-dimethylphenoxy)-2-amino-propane hydrochloride (Mexiletin). As an additional advantage, the compounds are devoid of the undesirable circulatory side effects, generally appearing upon the administration of the known antiarrhythmic agents, i.e. they fail to induce a pressure drop in the systemic circulation and a pressure increase in the pulmonary circulation in animals with intact chest or in unanaesthesized, permanently cannulated animals, at a dose range of 0.5 to 4.0 mg/kg. The antiarrhythmic effect of the compounds is not accompanied by any other activity affecting the vegetative nervous system, i.e. the compounds have neither alpha- nor beta-adrenergic blocking, nor adrenergic neurone blocking or parasympatholytic activity. 
     In addition, the compounds possess significant cardioprotective potency, i.e. their antiarrhythmic activity is also exhibited in the ischemic heart. This cardioprotective effect is three times higher than that of diethylamino-acet-(2,6-dimethyl)-anilide (Lidocain). 
     The compounds of the invention can be converted to pharmaceutical preparations by methods known in the art by applying additives, carriers and vehicles generally used in drug manufacturing. 
     A daily dose of 75 mg is planned for the treatment of human subjects weighing about 70 kg. 
    
    
     The following Examples are illustrating but not limiting the scope of the invention. 
     EXAMPLE 1 
     1-(2-Methylphenyl)-4,4-dimethyl-aminoguanidine hydrochloride 
     Method a. 
     A mixture of 1.59 g (0.01M) of 2-methyl-phenylhydrazine hydrochlorid, 3 ml of anhydrous n-propanol and 1 ml (0.0125M) of dimethyl-cyanamide is heated at 130° C. for 5 hours at continuous stirring and under nitrogen gas flow. To the resulting solution which is cooled to 0° C., 15 ml of hexane are added portion-wise. The precipitated white product is filtered on a glass filter, washed with a 4:1 mixture of hexane-ethanol and is dried. Yield 1.45 g (63.4 percent) of the product, m.p. 219° to 221° C. 
     Method b. 
     The procedure described under Method a. is applied except that n-butanol is used as solvent. Yield 1.33 g (58.2 percent) of the product, m.p. 219° to 221° C. 
     Method c. 
     The procedure described under Method a. is applied except that cyclohexanol is used as solvent. Yield 1.37 g (60.1 percent) of the product, m.p. 219° to 221° C. 
     Method d. 
     The procedure described under Method a. is applied except that the reaction is carried out without solvent, at 110° C. in a melted form. The resulting melt is suspended in a 4:1 mixture of hexane-ethanol, then it is filtered and dried. Yield 1.28 g (55.9 percent) of the product, m.p. 219° to 221° C. 
     EXAMPLE 2 
     1-(2,6-Dichlorophenyl)-4,4-dimethyl-aminoguanidine 
     The solution of 3.54 g (0.02M) of 2,6-dichlorophenylhydrazine, 6 ml of anhydrous n-propanol and 1.56 g (0.022M) of dimethyl-cyanamide is heated at 130° C. for 5 hours at continuous stirring and under nitrogen gas flow. The resulting solution is cooled to 0° C., then 60 ml of hexane are added portion-wise. The precipitated beige coloured product is filtered on a glass filter, it is washed with a 9:1 mixture of hexane-ethanol, and then dried. Yield 3.20 g (64.8 percent) of 1-(2,6-dichlorophenyl)-4,4-dimethyl-aminoguanidine, m.p. 153° to 154° C. 
     Preparation of the hydrochloride salt 
     The above base is dissolved in 10 ml of ethanol, then 10 ml of a saturated hydrochloric acid solution in ethanol are added to it dropwise at room temperature and at stirring. The resulting suspension is heated to 70° C. and it is stirred at this temperaturee for 30 minutes. The yellow solution is cooled to 40° C. and 80 ml of hexane are added to it at continuous stirring. The precipitated white product is filtered on a glass filter after cooling to 0° C., then it is washed with a 4:1 mixture of hexane-ethanol and dried. Yield 3.59 g (61.5 percent), m.p. 255° to 257° C. 
     EXAMPLE 3 
     1-(2-Chlorophenyl)-4,4-diethyl-aminoguanidine hydrochloride 
     The homogenized mixture of 2.14 g (0.015M) of 2-chloro-phenylhydrazine and 4.11 g (0.015M) of N,N-diethyl-S-methyl-isothiourea hydroiodide is cautiously melted at 110° C. under nitrogen flow. The melt is stirred for 1 hour at 110° C. and for 2 hours at 130° C. During the reaction methyl-mercaptan gas is liberated. When the gas formation has stopped, the dark red melt is cooled to room temperature, the solidified mass is dissolved in 15 ml of water, the solution is cooled to 0° C., the pH of this solution is adjusted to 8-9 with solid sodium hydrogencarbonate, then the precipitated beige-coloured crystals are filtered on a glass filter and washed with water having a temperature of 0° C. This wet product on the filter is dissolved in 25 ml of N hydrochloric acid at room temperature, the solution is decolourized with active carbon, then the solution is evaporated to dryness under reduced pressure. The evaporation residue is dissolved in 12 ml of anhydrous, hot ethanol, then it is cooled to 40° to 50° C., and portion-wise 50 ml of hexane are added to it. The precipitated white, crystalline plates are cooled to 0° C., filtered on a glass filter, washed with a 4:1 mixture of hexane and ethanol and dried. Yield 2.55 g (38.5 percent), m.p. 191.5° to 192.5° C. 
     EXAMPLE 4 
     1-(2-Methyl-phenyl)-4,4-diethyl-aminoguanidine hydrochloride 
     0.73 g (0.01M) of freshly distilled diethylamine is added to a solution of 3.23 g (0.01M) of 1-(2-methyl-phenyl)-3-(S-methyl)-isothiosemicarbazide hydroiodide in 10 ml of ethanol, and the solution is stirred at 40° C. for 72 hours. During the reaction methylmercaptan is generated. By the end of the reaction the solvent is evaporated at reduced pressure, the residue is dissolved in 10 ml of water, the solution is cooled to 0° C. and its pH is adjusted to 8-9 with solid sodium hydrogen carbonate. The precipitated beige-coloured product is filtered on a glass filter and washed with water having a temperature of 0° C. This wet material on the filter is dissolved in 13 ml of N hydrochloric acid at room temperature, the solution is decolourized with active carbon, and evaporated at reduced pressure to dryness. The evaporation residue is dissolved in a hot mixture of 10 ml of acetone and 2 ml of ethanol, the turbid solution is filtered, the filtrate is cooled to room temperature and 25 ml of ether are added to it. The precipitated, beige-coloured crystals are filtered on a glass filter following cooling to 0° C., washed with a 3:1 mixture of ether-acetone, and dried. Yield 0.95 g (37 percent), m.p. 174° to 176° C. 
     EXAMPLES 5 TO 54 
     The compounds presented in Table 6 can be prepared according to the procedures described in Examples 1 to 4. The Table lists the m.p. and the yield of the compounds, too. 
     
                                           TABLE 6                                 
__________________________________________________________________________
 No.Example                                                               
      R.sup.1                                                             
           R.sup.2                                                        
                R.sup.3                                                   
                     ##STR8##       R.sup.6                               
                                      R.sup.7                             
                                           %Yield                         
                                               M. p. °C.Hydrochlori
                                              de                          
__________________________________________________________________________
5    2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H    N(CH.sub.3).sub.2                                     
                                   H H    61  258-260                     
6    2-Cl H    H    N(CH.sub.3).sub.2                                     
                                   H H    69  252-253                     
7    2-CH.sub.3                                                           
          H    H                                                          
                     ##STR9##      H H    47  258-260                     
8    2-Cl H    H                                                          
                     ##STR10##     H H    45  212-213                     
9    H    H    3-Cl N(CH.sub.3).sub.2                                     
                                   H H    39  171-174                     
10   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H    N(C.sub.2 H.sub.5).sub.2                              
                                   H H    42  212-215                     
11   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR11##     H H    44  272- 275                    
12   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR12##     H H    23  233-237                     
13   2-CF.sub.3                                                           
          H    H    N(CH.sub.3).sub.2                                     
                                   H H    71  238-242                     
14   2-CF.sub.3                                                           
          H    H    N(C.sub.2 H.sub.5).sub.2                              
                                   H H    60  202-206                     
15   2-Cl 2-Cl H    N(CH.sub.3).sub.2                                     
                                   H H    63  257-258                     
16   2-CH.sub.3                                                           
          6-Cl H    N(CH.sub.3).sub.2                                     
                                   H H    40  256-258                     
17   2-CH.sub.3                                                           
          H    3-CH.sub.3                                                 
                    N(CH.sub.3).sub.2                                     
                                   H H    42  239-242                     
18   H    H    H    N(CH.sub.3).sub.2                                     
                                   H H    36  162-164                     
19   H    H    4-Cl N(CH.sub.3).sub.2                                     
                                   H H    58  192-200                     
20   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR13##     H H    75  245-247                     
21   2-CH.sub.3                                                           
          6-C.sub.2 H.sub.5                                               
               H    N(CH.sub.3).sub.2                                     
                                   H H    53  253-256                     
22   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR14##     H H    51  160-163                     
23   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR15##     H H    39  204-205                     
24   2-CH.sub.3                                                           
          H    3-Cl N(CH.sub.3).sub.2                                     
                                   H H    50  260-264                     
25   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               4-CH.sub.3                                                 
                    N(CH.sub.3).sub.2                                     
                                   H H    16  248-251                     
26   H    5-CH.sub.3 O                                                    
               4-CH.sub.3 O                                               
                     ##STR16##     H H    31  206-207                     
27   H    H    4-NO.sub.2                                                 
                    N(CH.sub.3).sub.2                                     
                                   H H    68  258-260                     
28   2-CH.sub.3 O                                                         
          H    H    N(CH.sub.3).sub.2                                     
                                   H H    39  95-97                       
29   2-CH.sub.3                                                           
          5-CH.sub.3                                                      
               H    N(CH.sub.3).sub.2                                     
                                   H H    41  238-240                     
30   2-CH.sub.3                                                           
          H    4-CH.sub.3                                                 
                    N(CH.sub.3).sub.2                                     
                                   H H    52  219-222                     
31   H    H    4-CH.sub.3                                                 
                    N(CH.sub.3).sub.2                                     
                                   H H    12  176-179                     
32   H    H    H    N(CH.sub.3).sub.2                                     
                                   H CH.sub.3                             
                                          46  196-200                     
33   H    H    H    N(CH.sub.3).sub.2                                     
                                   H i-propyl                             
                                          58   95-105                     
34   H    H    H    N(CH.sub.3).sub.2                                     
                                   H allyl                                
                                          41  161-163                     
35   2-CH.sub.3                                                           
          H    4-Cl N(CH.sub.3).sub. 2                                    
                                   H H    45  252-256                     
36   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR17##     H H    26  260-265                     
37   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR18##     H H    35  195-198                     
38   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR19##     H H    40  276-281                     
39   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR20##     H H    54  236-240                     
40   H    H    H    N(C.sub.2 H.sub.5).sub.2                              
                                   H CH.sub.3                             
                                          32  198-200                     
41   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR21##     H H    52  229-231                     
42   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR22##     H H    54  205-211                     
43   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR23##     H H    12  196-198                     
44   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR24##     H H    24  216-219                     
45   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR25##     H H    10  201-205                     
46   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR26##     H H    12  209-211                     
47   2-CH.sub.3                                                           
          H    H                                                          
                     ##STR27##     H H    28  198-204                     
48   3-Cl H    H                                                          
                     ##STR28##     H H    28  222-226                     
49   3-Cl H    H                                                          
                     ##STR29##     H H    27  228-230                     
50   2-Cl H    H                                                          
                     ##STR30##     H H    41  257-259                     
51   2-Cl H    H                                                          
                     ##STR31##     H H    42  219-221                     
52   2-Cl 6-Cl H                                                          
                     ##STR32##     H H    39  277-279                     
53   2-CH.sub.3                                                           
          6-CH.sub.3                                                      
               H                                                          
                     ##STR33##     H H    18  286-287 dihydroxide         
54   2-Cl H    H                                                          
                     ##STR34##     H H    35  224-226                     
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