as indicated above , the alkali metal salt employed in the practice of the invention may be any alkali metal salt corresponding to the formula : ## str7 ## wherein a , e , r , n , and m have the same meanings as given above . the alkali metal salt may be a salt of any alkali metal but is generally a salt of sodium , potassium , or lithium , preferably sodium . in other preferred embodiments , a is a pyridine ring , most preferably a 3 - pyridine ; e is oxygen ; r is methyl , ethyl , hexyl , or benzyl ; and n is 2 . exemplary of suitable salts are the sodium , potassium , and lithium salts of 4 - chloro - 2 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ] benzoic acid , 5 - bromo - 2 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ] benzoic acid , 5 - methoxy - 2 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ] benzoic acid , 3 , 5 - diiodo - 2 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ] benzoic acid , 2 -[( 1 - substituted - 3 - pyrrolidinyl ) oxy ] benzoic acids wherein the 1 - substituent is methyl , ethyl , isopropyl , cyclohexyl , benzyl , 4 - chlorobenzyl , 4 - methylbenzyl , 3 , 5 - dimethoxybenzyl , 3 - trifluoromethylbenzyl , 4 - nitrobenzyl , etc ., 3 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ]- 2 - naphthoic acid , 2 -[( 1 - substituted - 3 - pyrrolidinyl ) oxy ]- 3 - pyridine carboxylic acids wherein the 1 - substituent is methyl , ethyl , isopropyl , cyclohexyl , benzyl , 4 - chlorobenzyl , 4 - methylbenzyl , 4 - methoxybenzyl , 3 - trifluoromethylbenzyl , 4 - nitrobenzyl , etc ., 3 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ]- 4 - pyridine carboxylic acid , 4 -[( 1 - methyl - 3 - pyrrolindinyl ) oxy ]- 3 - pyridine carboxylic acid , 3 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ]- 2 - pyridine carboxylic acid , 2 -[( 1 - methyl - 3 - pyrrolidinyl ) thio ]- 3 - pyridine carboxylic acid , 2 -[( 1 - methyl - 3 - azetidinyl ) oxy ]- 3 - pyridine carboxylic acid , 2 -[( 1 - cyclohexyl - 3 - azetidinyl ) oxy ]- 3 - pyridine carboxylic acid , etc . a particularly preferred salt is sodium 2 -[( 1 - methyl - 3 - pyrrolidinyl ) oxy ]- 3 - pyridine carboxylate . when not available , the alkali metal salts can be prepared by conventional means , such as the syntheses of cale et al ., the teachings of which are incorporated herein in toto by reference . the syntheses are preferably conducted in the same solvent as will later be used in the halogenation / fusion reaction . when the alkali metal salts are pyridine compounds , a preferred method of synthesizing the compounds comprises reacting a precursor acid corresponding to the formula : ## str8 ## with a precursor alcohol corresponding to the formula : ## str9 ## in an inert solvent and in the presence of a non - nucleophilic alkali metal base , such as sodium or other alkali metal diisopropyl amide , sodium or other alkali metal hydride , etc . the acid and alcohol are usually reacted in substantially stoichiometric amounts , although either reactant can be employed in excess ; and the hydride or other alkali metal base is preferably employed in an amount sufficient to react with all of the hydroxyl groups of the acid and alcohol . the temperature employed for the reaction does not appear to be critical but is most commonly in the range of about 50 °- 150 ° c . and is preferably the reflux temperature of the solvent employed . the particular acids and alcohols employed in the reaction vary , of course , with the particular acid and alcohol moieties desired in the alkali metal salts , generally and most conveniently being the acids and alcohols that are the direct sources of those moieties . as indicated by the formula , the required substituent that is ortho to the carboxyl group of the acid may be any halo substituent , but availability and cost factors make the o - chloro and o - bromo acids the generally preferred acids , with the o - chloro compounds being most preferred . exemplary of the precursor acids that may be used are 2 - chloronicotinic acid , 3 - chloro - 4 - pyridine carboxylic acid , 4 - chloro - 3 - pyridine carboxylic acid , 3 - chloro - 2 - pyridine carboxylic acid , etc . suitable precursor alcohols include , e . g ., the 1 - substituted - 3 - pyrrolidinols , 1 - substituted 3 - azetidinols , and corresponding thiols wherein the 1 - substituent is methyl , ethyl , isopropyl , cyclohexyl , benzyl , 4 - chlorobenzyl , 4 - methylbenzyl , 3 , 5 - dimethoxybenzyl , 3 - trifluoromethylbenzyl , 4 - nitrobenzyl , etc . the solvent employed in the salt - forming reaction may be any inert solvent . however , in a preferred embodiment of the invention , the solvent used in the preparation of the alkali metal salt is one that will also be suitable for use in the halogenation / fusion reaction of the invention and in subsequent reactions that will be conducted when an aromatic 2 - aminoalkyl - 2 , 3 - dihydro - 1 , 4 - oxazepin - 5 ( 4h )- one or sulfur analog thereof is desired . such solvents include , e . g ., aromatic hydrocarbons such as benzene , toluene , xylene , etc . ; ethers such as diethyl ether , tetrahydrofuran , dioxane , etc . aromatic hydrocarbons such as toluene are generally preferred , and it is also preferred that the solvent have a boiling point in the range of about 50 °- 150 ° c . the halogenation / fusion reaction of the invention can be generally described as being the same as the halogenation / fusion reaction of cale et al . except for the use of oxalyl chloride or oxalyl bromide as the halogenating agent . thus , it is accomplished by mixing the alkali metal salt with the oxalyl halide in an inert solvent and heating at a suitable temperature to effect halogenation and , when necessary , subsequently neutralizing or basifying the halogenated compound , preferably with a tertiary amine such as triethylamine , and heating to effect fusion . in the preferred processes of the invention which utilize alkali metal salts wherein a is a pyridine ring , there is no need to use a tertiary amine or other fusion - inducing agent to effect fusion : the tendency toward fusion is so great that fusion inherently results from the conditions of the halogenation reaction . however , when the alkali metal salt is a compound in which a is a benzene or naphthalene ring , the added fusion - inducing agent is apt to be necessary . the amount of oxalyl halide employed in the reaction does not appear to be critical , but best results are apt to be obtained when the halogenating agent is used in at least a stoichiometric amount . the preferred halogenating agent varies , of course , with the product desired . however , oxalyl chloride is ordinarily preferred . the solvent employed in the halogenation / fusion reaction may be any inert solvent but is preferably a solvent , such as those mentioned above , which is also useful in the preparation of the alkali metal salt and in the preparation of derivatives of the 2 - haloalkyl product of the halogenation / fusion reaction . as in the alkali metal salt syntheses , aromatic hydrocarbons such as toluene are generally preferred . moreover , in a preferred embodiment of the invention , the solvent is the solvent in which the alkali metal salt was prepared and is incorporated by using , as the alkali metal salt , an alkali metal salt which is already suspended in the solvent in which it was prepared . the temperature employed for the reaction does not appear to be critical but is most conveniently the reflux temperature of the solvent , e . g ., a temperature in the range of about 50 °- 150 ° c . when the halogenation / fusion reaction has been completed , the 2 - haloalkyl product can be recovered by conventional means , such as the isolation techniques taught by cale et al ., if desired . however , in some cases , e . g ., when the reaction is conducted as a step in a process for preparing another aromatic 2 , 3 - dihydro - 1 , 4 - oxazepin - 5 ( 4h )- one or sulfur analog , it is preferred not to isolate the product but merely to remove the inorganic solids by filtration or a water wash and then to employ the solution of 2 - haloalkyl compound in the subsequent reaction . the product of the halogenation / fusion reaction can be used in the preparation of other aromatic 2 , 3 - dihydro - 1 , 4 - oxazepin - 5 ( 4h )- ones or sulfur analogs thereof by the procedures of cale et al . or other suitable procedures . for example : ( 1 ) the aromatic 2 - haloalkyl - 2 , 3 - dihydro - 1 , 4 - ox - or thiazepin - 5 ( 4h )- one may be aminated with an amine corresponding to the formula th to form the corresponding 2 - aminoalkyl compound and then , if desired , converted to a pharmaceutically - acceptable salt , ( 2 ) the 2 - haloalkyl compound or the corresponding 2 - aminoalkyl compound may be thiated to the corresponding thione , and , in the case of the amino compound , converted to a pharmaceutically - acceptable salt , if desired , and ( 3 ) the 2 - haloalkyl compound may be reacted with an alkali metal cyanide to form the corresponding 2 - cyanoalkyl compound and then , if desired , reduced to a primary amine and converted to a pharmaceutically - acceptable salt . in a preferred embodiment of the invention , the aromatic 2 - haloalkyl - 2 , 3 - dihydro - 1 , 4 - ox - or thiazepin - 5 ( 4h )- one , still in the toluene or other solvent in which it was prepared , is thiated to the corresponding thione and then aminated with a th amine to form the corresponding aromatic 2 - aminoalkyl - 2 , 3 - dihydro - 1 , 4 - oxor thiazepine - 5 ( 4h )- thione , which , when desired , is then converted to a pharmaceutically - acceptable salt . this process is particularly advantageous when the thiation is accomplished by the process of copending application ser . no . 770 , 603 , filed aug . 29 , 1985 , in the name of kenneth c . lilje , i . e ., by reacting the 2 - haloalkyl compound with phosphorus pentasulfide in the presence of an alkali metal bicarbonate and a hydrocarbon diluent . such a process , with its improved halogenation / fusion and thiation steps , as well as its use of the same solvent until the 2 - aminoalkyl compound has been formed , can result in product yields as high as about 60 - 65 %, based on the amount of precursor acid initially employed . thus , this overall process has a considerable advantage over the processes taught by cale et al ., whose yields have already been reduced to 27 % or less by the time they have completed their halogenation / fusion step -- a point in the reaction at which the present invention permits the attainment of yields as high as about 80 %. the following examples are given to illustrate the invention and are not intended as a limitation thereof . a 500 ml round - bottom flask equipped with a mechanical stirrer and reflux condenser was charged with 4 . 7 g of 60 % nah ( 2 . 5 g , 104 mmols nah ) and 150 ml of reagent grade toluene . to the stirred suspension was added 2 - chloronicotinic acid ( 8 . 2 g , 52 . 1 mmols ). then a solution of 5 . 26 g ( 52 . 1 mmols ) of 1 - methyl - 3 - pyrrolidinol in 20 ml of toluene was added dropwise to the mixture . the suspension was for 90 minutes , after which oxalyl chloride ( 6 . 6 g , 52 . 1 mmols ) in 20 ml of toluene was added . the resulting mixture refluxed for an additional 60 minutes , then cooled to ambient temperature . to the cooled suspension were added 25 ml of water 25 ml of 20 % na 2 co 3 solution . after 30 minutes the phases separated . the organic phase contained 10 . 0 g of 2 -( 2 - chloroethyl )- 2 , 3 - dihydro - 4 - methylpyrido [ 3 , 2 - f ]- 1 , 4 - oxazepin - 5 ( 4h )- one , an 80 % yield based on precursor acid . this solution can be concentrated to about 25 - 40 % and used directly in the next step . to 70 ml of toluene under nitrogen were added 4 . 1 g ( 9 . 25 mmols ) of phosphorus pentasulfide and 7 . 76 g ( 92 . 46 mmols ) of sodium bicarbonate . the resulting suspension was warmed to 90 ° c . and stirred for 30 minutes . to the resulting suspension was added a toluene solution ( 41 . 3 g ) containing 11 . 5 g ( 47 . 8 mmols ) of 2 -( 2 - chloroethyl )- 2 , 3 - dihydro - 4 - methylpyrido [ 3 , 2 - f ]- 1 , 4 - oxazepin - 5 ( 4h )- one dropwise over 40 minutes . the resulting mixture was heated to reflux . after one hour , tlc showed the starting material gone . the heat was removed and tetrahydrofuran ( 25 ml ) was added to the warm suspension . after the mixture had cooled to ambient temperature , water ( 11 ml ) was added , and stirring was continued for three hours . the resulting suspension was filtered . the organic phase in the filtrate was separated and found to contain 11 . 0 g of the desired oxazepinethione ( 90 % yield ). this solution is typically concentrated to 30 - 40 % and used as is in the next example . a fischer - porter tube was charged with a mixture of 5 g ( 19 . 5 mmols ) of 2 -( 2 - chloroethyl )- 2 , 3 - dihydro - 4 - methylpyrido [ 3 , 2 - f ]- 1 , 4 - oxazepine - 5 ( 4h )- thione , 8 . 7 g of toluene , and 15 ml of dimethylamine . the mixture was allowed to stir overnight at ambient temperature . the reactor was opened and the contents transferred to a separatory funnel with 20 ml of additional toluene . the mixture was washed with a solution made from 3 . 1 g of 25 % naoh and 3 . 3 g of water . the organic phase was evaporated to a viscous yellow oil which was dissolved in 40 ml of acetone and filtered . to the clear solution was added 1 . 9 g of concentrated hcl . the resulting suspension was stirred overnight . the product was collected via filtration , washed with acetone , and air dried , giving 5 . 4 g ( 87 % yield ). it is obvious that many variations can be made in the products and processes set forth above without departing from the spirit and scope of this invention .