ISOTHIAZOLONE DERIVATIVES

Abstract: There are disclosed compounds of the formula wherein R¹, R², m, o, R⁷ and the dotted line are defined in the text and the pharmaceutically acceptable salts thereof are useful as antipsychotic/anxiolytic agents having a low liability for extrapyramidal side effects.

Description: This invention relates to novel isothiazolone derivatives that are useful as pharmaceuticals, processes for their preparation and pharmaceutical derivatives containing them. DE 3321969A discloses that 2-(4-(4-(2-pyrimidinyl)-1-piperazinyl)butyl)-1 ,2-benzisothiazol-3(2H)-one--I ,1-dioxide and related compounds are anxiolytic agents. This invention relates to novel compounds having antipsychotic activity and being characterised by the general formula wherein R¹ and R² are each, independently, hydrogen, lower alkyl, aryl or halo, or R¹ and R² taken together represent -CH₂-, -CH₂CH₂ -, -O-, -NH-, -CH=CH-S-, =CH-S-CH=, -S-CH=CH-, where the dotted lines in formulae I, V, VI and VIII represent optional double bonds; R³, R⁴, R⁵ and R⁶ are each, independently, hydrogen, lower alkyl, aryl or halo; R⁷ is 2-pyridinyl, 2-pyrimidinyl, 2-pyrazinyl or 3-pyridazinyl or any of the foregoing R⁷ moieties substituted by lower alkyl, trifluoromethyl, cyano, nitro or halo, with the proviso that when R¹ and R² taken together represent then R⁷ is other than substituted or unsubstituted 2-pyridinyl or substituted or unsubstituted pyrimidin-2-yl; Z is (CH₂) n-, vinylene, -O-, or X is lower alkylene, vinylene, O or NH; m is 2 - 5; n is 0 - 4; o is 1 - 3; p is 1 - 4; and the pharmaceutically acceptable salts thereof. The term "lower alkyl" refers to moieties having 1 - 6 carbon atoms in the carbon chain. The term "lower alkylene" refers to moieties having 1 - 4 carbon atoms in the carbon chain. The term "aryl" refers to moieties having 6 - 12 carbon atoms. The term "halo" refers to fluoro, chloro and bromo. The compounds of the invention can form pharmacologically acceptable salts from pharmacologically acceptable organic and inorganic acids such as hydrochloric, hydrobromic, sulphuric, phosphoric. nitric, maleic, fumaric, benzoic, ascorbic, pamoic, succinic, methanesulphonic, acetic, propionic, tartaric, citric, lactic, malic, mandelic, cinnamic, palmitic, itaconic and benzenesulphonic. The invention also provides a process for the preparation of a compound having the formula I (wherein R¹, R², m, o, R⁷ and the dotted line are as defined above) or a salt thereof, in which (a) a cyclic amine having the formula A (wherein o and R⁷ are as defined above) or a salt thereof is alkylated to introduce the substituted alkyl group having the formula B by reaction with a compound having the formula R⁸-Y (wherein R⁸ is the group having formula B and Y is a leaving group, for example halo such as chloro or bromo); or (b) a cyclic amine having the formula A as defined and illustrated above or a salt thereof is subjected to reductive alkylation with an aldehyde having the formula C (wherein R¹, R², m and the dotted line are as defined (above); or (c) a compound having the formula D (wherein R¹, R² and the dotted line are as defined above) or a salt thereof is reacted with a compound having the formula E₁ or containing the cation E₂ (wherein m, o and R 7 are as defined above subject to the proviso that in formula E₂ m is 2 to 4 and o is 2 or 3 and Y is a leaving group, for instance a halo atom such as chloro or bromo); or (d) a compound having the formula F wherein R¹, R² , R⁷ , m, o and the dotted line are as defined above) or a salt thereof is (i) subjected to a Diels-Alder reaction by reaction with a compound having the formula G, H, J, K, L₁ or L₂ (wherein R³ , R⁴ R⁵ R⁶ , x, z, p and the dotted line are as defined above), (ii) subjected to epoxidation, (iii) subjected to carbene insertion or (iv) subjected to insertion of a nitrogen residue to form an aziridine of formula N below or a salt thereof; or (e) a compound having the formula M (wherein m, o and R⁷ are as defined above) or a salt thereof is reacted with a suitable nitrogen nucleophile to open the oxirane ring and the resultant intermediate is transformed into an aziridine having the formula N (wherein m, o and R⁷ are as defined above) or a salt thereof; or (f) a compound having the formula F as hereinbefore defined and illustrated or a salt thereof is reacted with a ketene having the formula O=C=CR³R⁴ (wherein R³ and R⁴ are as defined above) to prepare a compound having the formula P (wherein R³ , R 4 , m, o and R⁷ are as defined above) or a salt thereof; or (g) a compound having the formula P as hereinbefore defined and illustrated or a salt thereof is reduced to prepare a compound having the formula Q (wherein R³ , R⁴ , m, o and R⁷ are as defined above) or a salt thereof; or (h) a compound having the formula R (wherein R¹, R², m, o and R⁷ are as defined above and R⁹ is an organosulphonyl group for example methylsulphonyl) or a salt thereof is subjected to sulphinic acid elimination; or (j) an ethylenically unsaturated compound according to formula I or a salt thereof is reduced to form a saturated analogue thereof; or (k) a compound having formula I is converted into an acid addition salt thereof by addition of an acid or an acid addition salt of a compound having formula I is subjected to neutralisation to form the compound having formula I. Process step (a) can be carried out in a conventional manner for the preparation of tertiary amines by alkylation of secondary amines. In particular the reaction may be carried in a suitable solvent, for instance, dimethylformamide in the presence of an inorganic base or a tertiary amine. Process step (a) is preferably carried out synthetically by first reacting a compound having formula D in salt form with a dihaloalkane of the formula hal-(CH₂) m -hal (where m is as defined above and hal is chloro or bromo) and then reacting the resultant product of formula R⁸Y (where R⁸ is as defined above and Y is chloro or bromo) with the cyclic amine of formula A. Process step (b) may be carried out in conventional manner of preparation of tertiary amines from secondary amines and aldehydes by reductive alkylation. The reductive alkylation may be carried out with hydrogen and a platinum catalyst. The aldehyde of formula C may be prepared by reacting a compound of formula D in salt form with a compound having the formula hal-(CH₂) m-1 -CHO (wherein hal and m are as defined above). Process step (c) may be carried out in conventional manner for the alkylation of sulphonamide nitrogen atoms. The reaction may be carried out synthetically by first reacting the aforesaid dihaloalkane with the secondary amine of formula A to form the tertiary amine of formula E₁ where Y is halo and then reacting this product with the compound having formula D in salt form, e.g. as its sodium salt. Once a compound having formula I has been prepared by step (a), (b) or (c), it may be possible to convert it into other compounds having formula I. In particular a compound having formula F may be reacted with a diene of formula G, H, J, K, L₁ or L₂ to form a Diels-Alder reaction product. Alternatively a compound having formula F may be subjected to epoxidation or carbene insertion. These reaction may be carried out in known manner. The compound of formula M obtained as epoxidation product may be converted into an aziridine having formula N using various suitable nitrogen nucleophiles. For instance reaction of the oxirane with the isocyanate ion gives an intermediate which yields the aziridine on elimination of carbon dioxide. Another example of nucleophile is the azide ion according to the following reaction sequence: In addition aziridines may also be prepared according to step (d) (iv) by nucleophilic addition of the nitrogen residue to the ethylenic bond of the compound of formula F. Introduction of the nitrogen residue can be carried out via a Michael-type addition of a free sulphimide, for instance, diphenylsulphimide [see Chem. Abs. 93:46261j (1980)]. The compounds of formula F can also be used to prepare the compounds of formula P by reaction with a suitable ketene [step (f)]. Steps (d), (e), (f) and (g) may be carried out in known manner. Step (h) may carried out by heating and/or treatment with a base. Step (h) is particularly useful where it is desired to prepare compounds of formula I in which R¹ and R² together represent a residue of the type obtained by the Diels-Alder reaction and R¹ and R² are linked to adjacent carbon atoms joined by ethylenic unsaturation. Thus such compounds may be prepared by reacting a compound having the formula T (wherein R⁹, m, o and R⁷ are as defined above) with a diene of formula G, H, J, K, L₁ or L₂ and subjecting the resultant Diels-Alder reaction product to heating in the presence of a base to eliminate the sulphinic acid R⁹H. The saturated analogues of ethylenically unsaturated compounds discussed above can be prepared by hydrogenating the unsaturated compound according to step (j). The reduction may be carried out using hydrogen and Pd/C as a catatlyst. The compounds of the invention may exist either in the form of the free base or the pharmaceutically acceptable salts. The conversion of one such form into another by step (k) may be carried out in manner well known to one skilled in the chemical arts. Although steps (d) to (j) have been described with reference to the preparation of end products of formula I, a variety of intermediate compounds may be prepared in a similar manner using a compound containing a hydrogen atom or -(CH₂) m -hal group in place of the group having the formula Y For instance various compounds having formula D (D₂, D₃, D₄, D₅, D₆, D₇) may be prepared from 3-isothiazolone-1,1-dioxide (D₁) as shown below:- The starting materials used in the above-described preparative routes are commercially available or can be made according to procedures taught in the chemical literature. The invention also provides a pharmaceutical composition comprising a compound having the formula I or a pharmaceutically acceptable salt thereof in combination or association with a pharmaceutically acceptable carrier. The composition may be prepared by bringing the active compound into combination or association with the carrier. Included within the scope of the compounds having formula I and their pharmaceutically acceptable salts is the class of compounds wherein R¹ and R² are other than the group of formula V; R⁶ (if present) is hydrogen; R⁷ is 2-pyridinyl, halopyrimidin-2-yl, 2-pyrazinyl, halopyrazinyl, 2-pyridazinyl, halopyridazinyl, phenyl or phenyl substituted by lower alkyl, trifluoromethyl or halo and Z (if present) is -(CH₂) n -, -O- or a group of formula IV. The compounds of the invention display a pharmacological profile like that of the compound buspirone (8-[4-[4-(2-pyrimidinyl)-1-piperazinyl] butyl]-8-azaspiro[4.5]decane-7,9-dione). The latter compound has demonstrated preclinical activity in antipsychotic paradigms and has also displayed a unique clinical anxioselective profile, whereby its efficacy in the treatment of anxiety neuroses is comparable to the benzodiazepine diazepam but without the benzodiazepine-related side effects. The clinically effective anxiolytic doses of the benzodiazepines produce such undesirable side effects as ataxia, muscle relaxation and sedation. Additionally, most chronically used antipsychotic drugs, cause extrapyramidal side effects, such as pseudoparkinsonism, tardive dyskinesia and the like. Ideally, treatment of psychoses and anxiety should be free of any undesirable side effects. The compounds of the invention, in a manner similar to buspirone, display antipsychotic activity without or with minimal side effects. Moreover, based on their buspirone-like profile, the compounds of the invention can be considered of clinical value in treating anxiety neuroses. When employed as anxiolytics/antipsychotics, the effective dosage of the substances active for such treatment will vary according to the Particular compound being employed, the severity and nature of condition being treated. Therapy should be initiated at lower doses, the dosage thereafter being increased, if necessary, to produce the desired effect. In general, the compounds of the invention are most desirably administered at a concentration that will generally afford effective results without causing any harmful or deleterious effects. When the compounds of the invention are employed as anxiolytics/anti-psychotic agents, they can be formulated into oral dosage forms such as tablets, capsules and the like. The compounds can be administered alone or by combining them with conventional carriers, such as magnesium carbonate, magnesium stearate, talc, sugar, lactose, pectin, dextrin, starch, gelatin, tragacanth, methylcellulose, sodium carboxymethylcellulose, low melting wax, cocoa butter and the like. Diluents, flavoring agents, solubilizers, lubricants, suspending agents, binders, tablet-disintegrating agents and the like may be employed. The compounds may be encapsulated with or without other carriers. In all cases, the proportion of active ingredients in said compositions both solid and liquid will be at least to impart the desired activity thereto on oral administration. The compounds may also be injected parenterally in which case they are used in the form of a sterile solution containing other solutes, for example, enough saline or glucose to make the solution isotonic. The antipsychotic activity of the compounds of the invention and their substantial lack of extrapyramidal side effects may be demonstrated by standard pharmacological procedures, which are described more fully in the examples given hereafter. The following examples show the preparation and pharmacological testing of compounds within the invention. Example 1 3a,4,7,7a-Tetrahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide,dihydrochloride,hemihydrate To a solution of 3 g (0.02 mol) of 3a,4,7,7a-tetrahydro-4 ,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide in 50 mL of dimethylformamide is added 0.6 g (0.03 mol) of sodium hydride and the reaction mixture is stirred for 1 hour. While stirring, 3 g (0.02 mol) of 1-bromo-4- chlorobutane is added and stirring is continued for 48 hours. The dimethylformamide is removed under reduced pressure and the remaining semisolid is extracted with methylene chloride (3 x 100 mL), the methylene chloride layer is washed with water, dried (over anhydrous Na₂SO₄) and evaporated under reduced pressure. The semisolid which separates (4.0 g; 54% yield) is analyzed by IR and NMR, and spectral data are consistent for 3a,4,7,7a-tetrahydro-2-[4-chloro-1-butyl ]-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide. The title compound is prepared by dissolving 4 g (0.01 mol) of 3a,4,7,7a-tetrahydro-2-[chloro-1-butyl ]-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide in dimethylformamide (60 mL), to which is added 6 mL of triethylamine and 2.3 g (0.01 mol) of 4-(2-pyrimidinyl)piperazine. The reaction mixture is stirred for 48 hours at room temperature. The dimethylformamide is removed under reduced pressure and the remaining solid is dissolved in 30 mL of water and extracted with methylene chloride (3 x 300 mL). The methylene chloride extract is washed with water and dried (over anhydrous Na₂SO₄). Evaporation of the methylene chloride under reduced pressure gives a yellow semisolid. TLC analysis indicates the presence of the title compound and other impurities. The title compound is separated by HPLC on a silica gel column using 30% methanol-ethyl acetate as eluent. Evaporation of the solvent from the desired fraction R f 0.5 affords 0.8 g (20% yield) of the free base form of the title compound, mp 118-120°C, which is converted to the dihydrochloride by dissolving the free base in ethanol and adding ether saturated with hydrogen chloride, mp 220-222°C. Analysis for: C₂₀H₂₇NSO₃·2HCl·1/2 H 2 O Calculated: C, 48.09; H, 6.01; N, 14.02; C1, 14.66 Found: C, 48.27; H, 5.91; N, 14.01; C1, 14.48. Example 2 3a,3,7,7a-Tetrahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,7-ethano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide,dihydrochloride,hydrate The free base form of the title compound is prepared following the procedure of Example 1 using 3a,4,7,7a-tetrahydro-4,7-ethano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide instead of 3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1 -dioxide and is converted to the dihydrochloride hydrate; mp 258-260°C. Analysis for: C₂₁H₂₉N₅O₃S·2HCl·H 2 O Calculated: C, 48.27; H, 6.37; N, 13.41 Found: C, 48.45; H, 6.38; N, 12.75. Example 3 3a,4,7,7a-Tetrahydro-5,6-dimethyl-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]-butyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide dihydrochloride, The free base form of the title compound is prepared using the procedure of Example 1 using 3a,4,7,7a- tetrahydro -5,6-dimethyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide instead of 3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1 -dioxide and is converted to the dihydrochloride salt, mp 160-162°C. Analysis for: C₂₁H₃₁N₅SO₃·2HCl·1 1/2 H₂O Calculated: C, 47.27; H, 6.79; N, 13.12 Found: C, 47.13; H, 6.23; N, 12.85. Example 4 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a-tetrahydro-5,6-dimethyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide,dihydrochloride The free base form of the title compound is prepared using the procedure of Example 1 using 3a,4,7,7a-tetrahydro-5,6-dimethyl-1,2-benzisothiazol-3-(2H)-one 1,1-dioxide instead of 3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide and 1-(6-chloro-2-pyrazinyl)piperazine instead of 4-(2-pyrimidinyl)piperazine. The final product is converted to its dihydrochloride salt, mp 158-160°C. Analysis for: C₂₁H₃₀N₅ClSO₃·2HCl Calculated: C, 46.62; H, 5.96; N, 12.95 Found: C, 46.14; H, 5.43; N, 14.83. Example 5 2-[4-[4-(6-chloro-2-pyrazinyl]-1-piperazinyl] butyl]-3a,4,7, 7a-tetrahydro-4,7-ethano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide,hydrochloride A. 3a,4,7,7a-Tetrahydro-2-[4-bromobutyl]-4,7-ethano-1,2-benzisothiazol-3-(2H)-one 1,1-dioxide A solution of 456 mg (19 mmol) of sodium hydride (prepared from 760 mg of 60% sodium hydride in mineral oil by pentane wash) in 40 ml of dimethylformamide is treated portionwise with 4.05 g (19 mmol) of 3a,4,7,7a-tetrahydro-4,7-ethano-1,2-benzisothiazol-3(2 H )-one-1,1-dioxide at 0°C. The resulting solution is added dropwise to a solution of 12.3 g (57 mmol) of 1,4-dibromobutane in 40 ml of dimethylformamide. The mixture is maintained with stirring at room temperature for 22.5 hours. The solvent is removed under high vacuum and the residue partitioned between methylene chloride and water. The combined methylene chloride extracts are washed with brine and dried over MgSO₄. Filtration and removal of solvent in vacuo gives an oily solid which is triturated with ethyl ether and filtered to give 1 .05 g of the title compound, mp 118-122°C. Analysis for: C₁₃H₁₈BrNO₃S Calculated: C, 44.83; H, 5.21; N, 4.02 Found: C, 44.87; H, 5.07; N, 3.93. B. 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a- tetrahydro-4,7-ethano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride A solution of 1.0 g (2.9 mmol) of 3a,4,7,7a-tetrahydro-2-(4-bromobutyl)-4,7-ethano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide in 25 ml of anhydrous dimethylformamide is treated with 1.6 g (16 mmol) of triethylamine and 866 mg (3.2 mmol) of 1-(6-chloro-2-pyrazinyl)piperazine, monohydrochloride salt. The mixture is maintained at room temperature with stirring for 15 hours and then is partitioned between water and methylene chloride. The methylene chloride extracts are combined, dried over MgSO₄, filtered and rotoevaporated to give crude free base. Preparative HPLC (silica gel; ethyl acetate: methylene chloride (9:1)) followed by evaporation of the appropriate fractions, treatment with ethanolic hydrochloric acid and recrystallization from methanol gives the title compound: mp. 263-267°C. Analysis for: C₂₁H₂₈N₅O₃SCl·HCl Calculated: C, 50.19; H, 5.82; N, 13.94 Found: C, 49.99; H, 5.78; N, 13.80 Example 6 4,4a,5,5a,6,6a-hexahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,6-etheno-2H-cyclopropa[f][1,2}benzisothiazol-3(3aH)-one 1,1-dioxide,dihydrochloride A. 4,4a,5,5a,6,6a-hexahydro-2-(4-bromobutyl)-4,6-etheno-2H-cyclopropa[f]-[1,2] benzisothiazol-3(3aH)-one 1,1-dioxide A solution of 648 mg (27 mmol) of sodium hydride (prepared from 1.08 g of 60% sodium hydride in mineral oil by pentane wash) in 50 ml of dimethylformamide is treated portionwise at 10°C with 5.45 g (24 mmol) of 4,4a,5,5a,6,6a-hexahydro-4,6-etheno-2 H -cyclopropa[f][1,2]benzisothiazol-3(3a H )-one 1,1-dioxide. When gas evolution ceases, the solution is added dropwise to a solution of 25.9 g (120 mmol) of 1,4-dibromobutane in 100 ml of dimethylformamide. The mixture is maintained with stirring for 18 hours and then is partitioned between methylene chloride and aqueous sodium bicarbonate. The combined organic extracts are dried over MgSO₄, filtered, rotoevaporated and residual solvent removed under high vacuum. The solid residue is crystallized from isopropyl ether to give 4.5 g of the title compound: mp 96-100°C. Analysis for: C₁₄H₁₈BrNO₃S Calculated: C,46.67;H,5.03; N, 3.88 Found: C, 45.28; H,4.99;N,4.42 B. 4,4a,5,5a,6,6a-hexahydro-2-[4-(2-pyrimidinyl)-1-piperazinyl] butyl] -4,6-etheno-2H-cyclopropa[f][1,2]benzisothiazol-3(3aH)-one 1,1-dioxide, dihydrochloride A solution of 1.8 g (5 mmol) of 4,4a,5,5a,6,6a- hexahydro-2-(4-bromobutyl)-4,6-etheno-2H-cyclopropa[f] [1,2]benzisothiazol-3(3a H )-one 1,1-dioxide in 10 ml of dimethylformamide is added dropwise to a solution of 980 mg (6 mmol) of 4-(2-pyrimidinyl)piperazine dihydrochloride containing 3.0 g (30 mmol) of triethylamine and 1.6 g (5 mmol) of cesium carbonate over 2.5 hours. The mixture is stirred at room temperature for 17 hours and then is partitioned between methylene chloride and water. The combined organic extracts are dried over MgSO₄, filtered and evaporated under high vacuum to give crude product. Column chromatography (silica gel; ethyl acetate) gives 577 mg of free base. Treatment with ethanolic hydrochloric acid and recrystallization from absolute ethanol gives the title compound; mp. 233-240°C. Analysis for: C₂₂H₂₉N₅O₃S ·2HCl Calculated: C, 51.16; H, 6.05; N, 13.56 Found: C, 50.51; H, 5.97; N, 13.36 Example 7 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-4,4a,5,5a,6,6a-hexahydro-4,6-etheno-2H-cyclopropa[f][1,2]-benzisothiazol-3(3aH)-one 1,1-dioxide,hydrochloride The title compound is prepared following the procedure of Example 6B using 1-(6-chloro-2-pyrazinyl)piperazine hydrochloride instead of 4-(2-pyrimidinyl)piperazine dihydrochloride: mp. 255-257°C (dec). Analysis for: C₂₂H₂₈ClN₅O₃S · HCl Calculated: C, 51.36; H, 5.68; N, 13.61 Found: C, 51.76; H, 5.79; N, 13.51 Example 8 3a α,4ß,7ß,7a α₋hexahydro-2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide,hydrochloride A solution of 3.5 g (10.4 mmol) of (3aα,4ß,7ß,7aα)- hexahydro-2-(4-bromobutyl)-4₁7-epoxy-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide in 150 ml of dimethylformamide is treated with 8.6 g (84 mmol) of triethylamine and 4.9 g (21 mmol) of 1-(6-chloro-2-pyrazinyl)piperazine. The mixture is stirred at room temperature for 24 hours, 8.6 g (84 mmol) of triethylamine is added and stirring continued for 18 hours. The mixture is partitioned between methylene chloride and water. The combined organic extracts are dried over MgSO₄, filtered and evaporated to given an oil. Trituration with ethyl acetate gives a solid which is subjected to preparative HPLC (silica gel; ethyl acetate). The fractions containing the component at Rf 0.15 (ethyl acetate) are evaporated and crystallized from ethyl acetate to give 1.1 g of free base of the title compound: mp 147-149°C. Analysis for: C₁₉H₂₆ClN₅SO₄ Calculated: C, 50.05; H, 5.75; N, 15.36 Found: C, 49.93; H, 5.74; N, 15.32 The free base is treated with ethanolic hydrochloric acid and crystallized twice from absolute ethanol to give the title compound: mp 231 - 235°C. Analysis for: C₁₉H₂₆ClN₅SO₄.HCl Calculated: C, 46.34; H, 5.53; N, 14.22 Found: C, 46.14; H, 5.39; N, 13.88 Example 9 2-[4-[4-(6-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride A mixture of saccharin (3.69 g, 0.02 mol), sodium hydride 0.5 g, 1-bromo-4-chlorobutane (5.2 g, 0.03 mol) and 50 ml of dimethylformamide is stirred at room temperature for 48 hours. The solvent is evaporated under reduced pressure and the brown residue is extracted with methylene chloride (3 x 200 ml). The methylene chloride extracts are collected, washed with water and dried (anhydrous Na₂SO₄). Evaporation of the methylene chloride under reduced pressure affords 5 g of 2-(4-chlorobutyl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide. The title compound is prepared by dissolving 2.5 g (0.008 mol) of 2-(4-chlorobutyl)-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide in 50 ml of dimethylformamide and to that solution 2.5 g (0.01 mol) of 1-(6-chloro-2-pyrazinyl)-piperazine hydrochloride and 5 ml of triethylamine are added. Stirring is continued for 48 hours. The solvent is removed under reduced pressure and the residue is partitioned between water and methylene chloride. The methylene chloride extracts are combined, dried over anhydrous Na₂SO₄, filtered and evaporated under reduced pressure to give crude base. Preparative HPLC (silica gel; ethylacetate:methylene chloride (9.1)) gives, following evaporation of the appropriate fractions (R f 0.5), the free base form of the title compound, which is converted to the hydrochloride salt; mp 246-249C. Analysis foar: C₁₉H₂₂ClN₅O₃·HCl Calculated: C, 48.30; H, 4.87; N, 14.83 Found: C, 48.03; H, 4.89; N, 14.06 Example 10 2-[4-[4-(6-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]thieno[3,4-d]-isothiazol-3(2H)-one 1,1-dioxide hydrochloride The free base form of the title compound is prepared following the procedure of Example 9 using thiophene saccharin instead of saccharin and is converted to the hydrochloride salt; mp 255-256°C. Analysis for: C₁₇H₂₀ClN₅S₂O₃·HCl Calculated: C, 42.67; H, 4.39; N, 14.64 Found: C, 43.09; H, 4.29; N, 14.84 Example 11 2-[4-[4-(3-Chloro-2-pyrazinyl)-piperazinyl]butyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride The free base form of the title compound is prepared following the procedure of Example 9 using 1-(3-chloro-2-pyrazinyl)piperazine hydrochloride instead of 1-(6-chloro-2-pyrazinyl)piperazine hydrochloride and is converted to the hydrochloride salt; mp 229-231°C. Analysis for: C₁₉H₂₂ClN₅O₃SHCl·1/2 H₂O Calculated: C, 47.40; H, 4.98; N, 14.55 Found: Ct 47.61; H, 4.94; N, 14.49. Example 12 2-[4-[4-(3-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]thieno[3,4-d]isothiazol-3(2H)-one 1,1-dioxide, hydrochloride, hemipentahydrate The free base form of the title compound is prepared following the procedure of Example 9 using thiophene saccharin instead of saccharin and 1-(3-chloro-2-pyrazinyl)piperazine hydrochloride instead of 1-(6-chloro-2-pyrazinyl)-piperazine hydrochloride and is converted to the hydrochloride salt; mp 243-245°C. Analysis for: C₁₇H₂₀N₅S₂ClO₃·HCl·2 1/2 H₂O Calculated: C, 38.90; H, 4.77; N, 13.37 Found: C, 38.20; H, 4.93; N, 13.85. Example 13 2-[4-[4-(3-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a-tetrahydro-5,6-dimethyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride, hydrate The free base form of the title compound is prepared using the procedure of Example 1, using 3a,4,7,7a-tetrahydro-5,6-dimethyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide instead of 3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide and 1-(3-chloro-2-pyrazinyl)piperazine hydrochloride instead of 1-(2-pyrimidinyl)piperazine and is converted to the hydrochloride salt; mp 95-97°C. Analysis for: C₂₁H₃₀ClN₅SO₃·HCl·H₂O Calculated: C, 48.36; H, 6.14; N, 13.43 Found: C, 48.80; H, 6.25; N, 13.30. Example 14 2-[4-[4-(6-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, dihydrochloride The free base form of the title compound is prepared following the procedure of Example 1 and using 1-(6-chloro-2-pyrazinyl)piperazine hydrochloride instead of 1-(2-pyrimidinyl)piperazine and is converted to the hydrochloride salt; mp 235-237°C. Analysis for: C₂₀H₂₆ClN₅SO₃·2HCl Calculated: C, 45.75; H, 5.52; N, 13.34 Found: C, 46.06; H, 5.55; N, 12.97. Example 15 2-[4-[4(2-Pyrimidinyl)-1-piperazinyl]butyl]-3a,4,5,6,7,7a-hexahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, dihydrochloride, hemihydrate The free base form of the title compound is prepared following procedure of Example 1 and using 3a,4,5,6,7,7a-hexahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide instead of 3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide and is converted to the hydrochloride salt; mp 214-215°C. Analysis for: C₂₀H₂₉SN₅O₃·2HCl·1/2 H₂O Calculated: C, 47.90; H, 6.38; N, 13.97 Found: C, 48.04; H, 6.15; N, 13.74. Example 16 2-[4-[4-(6-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,5,6,7,7a-hexahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride The free base form of the title compound is prepared following the procedure of Example 1 and using 3a,4,5,6,7,7a-hexahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one, 1,1-dioxide instead of 3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide and 1-(6-chloro-2-pyrazinyl)-l-piperazine hydrochloride instead of 1-(2-pyrimidinyl)piperazine and is converted to the hydrochloride salt; mp 240-242°C. Analysis for: C₂₀H₂₈ClSN₅O₃·HCl Calculated: C, 48.97; H, 5.91; N, 14.28 Found: C, 49.15; H, 6.00; N, 14.08. Example 17 Hexahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl-4,6-ethano-2H-cycloprop[f]-12-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride A. Hexahydro-4,6-ethano-2H-cycloprop[f]-1,2-benzisothiazol-3(3aH)-one 1,1-dioxide To a stirred suspension of 3-isothiazolone 1,1-dioxide in 100 ml of xylene, 5.2 ml (0.05 mol) of 1,3,5-cycloheptatriene is added. The reaction mixture is refluxed 5 hrs, then allowed to cool. The separated solid is filtered and dried to afford 2.2 g of 4,4a,5,5a,6,6a-hexahydro-4,6-ethano-2 H -cycloprop-[f]-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide; mp 179-182°C. A solution of 2.2 g of 4,4a,5,5a,6,6a-hexahydro-4,6-etheno-2 H -cycloprop[ f ]-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide in 50 ml of ethanol is hydrogenated in the presence of 2 g of 10% Pd/C for 24 hours. The catalyst is filtered and the solvent is evaporated under reduced pressure to aford 2 g of hexahydro-4,6-ethano-2 H -cycloprop[ f ] 1,2-benzisothiazol-3(3a H )-one 1,1-dioxide. B. Hexahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,6-ethano-2H-cycloprop[f]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride The free base form of the title compound is prepared following the procedure of Example 6 using hexahydro-4,6-ethano-2 H -cycloprop[ f ]-1,2-benzisothiazol-3(3a H )-one 1,1-dioxide instead of 4,4a,5,5a,6,6a-hexahydro-4,6-etheno-2 H -cycloprop[ f ]-1,2-benzisothiazol-3(3a H )-one 1,1-dioxide and is converted to the hydrochloride salt; mp 250-251°C. Analysis for: C₂₂H₃₁N₅O₃S·HCl Calculated: C, 54.81; H, 6.69; N, 14.53 Found: C, 54.61; H, 6.70; N, 14.02. Example 18 3aα,4β,7β,7aα)-Hexahydro-2-[4-[4-(2-pyrazinyl)-1-piperazinyl]butyl]-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, dihydrochloride, hemihydrate A. (3aα,4β,7β,7aα)Hexahydro-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide A mixture of 5.2 g of 3-isothiazolone 1,1-dioxide and 5 ml of furan in 100 ml benzene is refluxed for 2 hours. An additional 5 ml of furan is added and the refluxing is continued for an additional hour; after cooling, the separated solid is filtered. It affords 7.5 g of a 2:1 mixture of exo:endo cycloadduct; mp 170-171°C. The exoadduct is (3aα,4β,7β,7aα)-tetrahydro-4,7-epoxy-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide. The endoadduct is (3aα,4α,7α,7aα)-tetrahydro-4,7-epoxy-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide. The exo product (10.0 g) is dissolved in 100 ml of tetrahydrofuran and is hydrogenated over 2 g of Pd/C (10%) for 30 minutes. The catalyst is filtered and the solvent is evaporated under reduced pressure to afford 9.8 g of the reduced cycloadduct (3aα,4β,7β,7aα)-hexahydro-4,7-epoxy-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide; mp 209-212°C. Analysis for: C₇H₉SNO₄ Calculated: C, 41.85; H, 4.52; N, 6.89 Found: C, 41.37; H, 4.46; N, 6.89. B. 3aα,4β,7β,7aα)-Hexahydro-2-[4-[4-(2-pyrazinyl)-1-piperazinyl]butyl]-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, dihydrochloride, hemihydrate The free base form of the title compound is prepared following the procedure of Example 8, using 1-(2-pyrazinyl)piperazine hydrochloride instead of 1-(6-chloro-2-pyrazinyl)piperazine hydrochloride and is converted to the hydrochloride salt; mp 186-198°C. Analysis for: C₁₉H₂₇N₅SO₄ Calculated: C, 45.32; H, 6.01; N, 13.91 Found: C, 45.40; H, 5.91; N, 13.51. Example 19 (3aα,4α,7α,7aα)-2-[4-[4-(6-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]hexahydro-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, hydrochloride The free base form of the title compound is prepared following the procedure of Example 8, using (3aα,4α,7α,7aα)-hexahydro-4,7-epoxy-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide instead of (3aα,4β,7β,7aα)-hexahydro-4,7-epoxy-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide and is converted to the hydrochloride salt; mp 268-277°C. Analysis for: C₁₉H₂₆ClN₅SO₄·HCl Calculated: C, 46.34; H, 5.53; N, 14.22 Found: C, 46.34; H, 5.48; N, 14.01. Example 20 3a,4,4a,6a,7,7a-Hexahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,7-ethenocyclobut[f]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide, dehydrochloride A. 3a,4a,6a,7,7a-Hexahydro-4,7-ethenocyclobut[f]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide To a boiling solution of 3-isothiazolone 1,1-dioxide (2.8 g) is added 2 g of cyclooctatetraene portionwise and refluxing is continued for 16 hrs. The mixture is decanted and chilled in ice. The resulting crystalline product is separated and filtered to afford 1.92 g of 3a,4a,6a,7,7a-hexahydro-4,7-ethenocyclobut[ f ]-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide; mp 207-215°C. Analysis for: C₁₁H₁₁SNO₃ Calculated: C, 53.76; H, 4.52; N, 5.89 Found: C, 53.68; H, 4.67; N, 5.90. B. 3a,4,4a,6a,7,7a-Hexahydro-2-[4-[4-(2-pyrimidinyl-1-piperazinyl]butyl]-4,7-ethenocyclobut[f]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide dihydrochloride The free base form of the title compound is prepared following the procedure of Example 1, using 3a,4a,6a,7,7a-hexahydro-4,7-ethenocyclobut[ f ]-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide instead of 3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2 H )-one 1,1-dioxide and is converted to the hydrochloride salt; mp 222-234°C. Analysis for: C₂₃H₂₉N₅O₃S·2HCl Calculated: C, 52.27; H, 5.91; N, 13.25 Found: C, 52.82; H, 5.89; N, 12.65. Example 21 The compounds of the invention are tested in an assay to determine their ability to antagonize apomorphine-induced stereotyped behavior. The assay measures the in vivo dopamine receptor blocking activity of the compounds and provides a means for gauging whether the compounds tested may potentially exhibit extrapyramidal side effects. The assay is carried out as follows: 20-25 gm male CF-1 mice (Charles River) are used. The mice are tested one week before the experiment for a positive stereotyped response to 10 mg/kg s.c. apomorphine. Test compounds, suspended or solubilized in 0.25% Tween 80 ® in water, are administered at several dose levels to male mice (6/dose level). A control group, run simultaneouly with drug groups, receives equal volumes of solvent. Thirty minutes later (i.p. administration), drug-treated and control mice are challenged with 10 mg/kg apomorphine s.c. Five minutes after the injection, the rearing-head-bobbing-licking syndrome induced by apomorphine is recorded as present or absent for each animal. Readings are repeated every 5 minutes during a 30 minute test session. The number of positive or negative 5-minute intervals during which apomorphine-induced stereotyped behavior is present or absent is measured. ED₅₀ values (with 95% confidence intervals) are calculated for inhibition of apomorphine-induced stereotyped behavior, by a simple linear regression analysis with inverse prediction. STANDARD COMPOUNDS: ED₅₀ and 95% confidence interval, mg/kg The compounds of the invention and buspirone, when tested in this assay are inactive, evidencing a low potential for exhibiting extrapyramidal side effects, such as pseudoparkinsonism, tardive dyskinesia and the like. Example 22 The compounds of the invention are further studied for their ability to inhibit limbic D-2 dopamine receptor binding. This in vitro assay measures the ability of the compounds tested to bind to the dopamine receptor sites. Those compounds which exhibit a weak binding effect have a low liability to display potential extrapyramidal side effects. The assay is carried out as follows: Several rats are decapitated and the brains are rapidly removed. Limbic brain tissue (nucleus accumbens, septal area, olfactory tubercle) is dissected and homogenized on ice in 9 volumes of buffer (50 mM Tris-HCl, 120 mM NaCl, 5 mM KCl, 1 mM CaCl₂, 1 mM MgCl₂, 0.1% L-ascorbic acid, 10 µM pargyline HCl, pH 7.1) using a Polytron homogenizer at setting 5 for three 15-sec bursts. The homogenate is then diluted 4-fold with buffer and centrifuged at 30,000 x g for 20 min, and the supernatant is discarded. The pellet is resuspended in the same volume of buffer and recentrifuged as before, again discarding the supernatant. This pellet is then resuspended in the same volume of buffer used in the homogenization, and the protein content of this preparation is assayed by the Lowry method. The homogenate is stored frozen at -70°C until use. Thirty µL of the homogenate (0.2-0.3 mg protein/sample) are incubated with 0.3 nM ³H-spiroperidol (New England Nuclear) and various concentrations of test drug in a final volume of 1 ml of the above buffer for 10 min in a 37°C water bath. At the end of the incubation, 3 ml of cold 50 mM Tris-HCl, pH 7.7, are added to each tube, and the contents are rapidly vacuum-filtered through Whatman GF/B glass-fiber filters. The filters are then rapidly washed 3 times with 3 ml of the same buffer, placed in scintillation vials, and shaken for 15 min with 10 ml of Hydrofluor (National Diagnostics) scintillation cocktail. The vials are then counted in a Packard 460CD scintillation counter. Specific binding is defined as total binding less binding in the presence of 1 µM (+)butaclamol. Binding in the presence of various concentrations of test drug is expressed as a per cent of specific binding when no drug is present. These results are then plotted as logit % binding vs. log concentration of test drug. Linear regression analysis then yields a straight line with 95% confidence limits from which an IC₅₀ can be inversely predicted. K i (inhibition constant) for the test drug is then calculated by the formula: The results of testing of some of the compounds of the invention, and the prior art compound buspirone (8-[4-[4-(2-pyrimidinyl)-1-piperazinyl] butyl]-8-azaspiro[4.5] decane-7,9-dione) in this assay are presented in Table 1. The results show that the compounds of the invention display a very weak effect, evidencing a low potential for extrapyramidal side effects. Example 23 The antipsychotic activity of the compounds of the invention is assessed via the conditioned avoidance (discrete trial) test. This test has excellent clinical correlation for antipsychotic activity. The test is carried out as follows: Male CD rats (Charles River) maintained at approximately 400-450 gm body weight are used. Rats trained previously are placed in plexiglass experimental chambers equipped with a response lever, house light, and sonalert. A steel grid floor is wired for presentation of electric shock. Each trial consists of a fifteen-second warning tone (conditioned stimulus), continuing for an additional fifteen seconds accompanied by electric shock, (unconditioned stimulus). The rat can terminate a trial at any point by depression of the response lever. A response during the initial fifteen-second warning tone ends the trial before shock delivery and is considered an avoidance response, while a response occurring during shock delivery is an escape response. Trials are presented on a variable interval schedule of two minutes. The session consists of sixty trials. Animals are run two to three times weekly with control sessions always preceding a drug run, and with at least one day intervening, compounds are administered i.p. or p.o. at appropriate pre-treatment times to a minimum of five to six rats at each dose level over a range of doses. The following experimental parameters are recorded by computer: (1) the number of intertrial interval responses, (2) the number of avoidance responses, (3) the number of escape responses, and (4) the number of trials in which no response occurred. These data are used to calculate the percent difference from control values previously determined and are presented for visual comparison via a line graph. Response counts are summed over all subjects at a given dose. The number of trials in which rats fail to exhibit an avoidance response (Avoidance Block, AB) is determined at each dose. This number is expressed as a percentage of the total trials. Control performance is arbitrarily assigned a value of 100% for avoidance and the dose calculated to produce a 50% block in avoidance responding (AB₅₀) is obtained from a dose-effect regression line fitted by the method of least squares. Potential antipsychotic compounds suppress avoidance responding and increase escape responding. The results for a compound of this invention in this test is presented in Table 2. Compounds of Example numbers 15, 16, 17, 7,19, and 20 all showed activity in this assay at 40 mg/kg perorally administered. The results show the compounds tested to have activity comparable to that of buspirone when orally administered. Example 24 Another test designed to determine the potential antipsychotic activity of the compounds of the invention is the conditioned avoidance (shelf-jump response) test. This test is carried out as follows: Male CD rats (Charles River) maintained at approximately 400-450 gm body weight are used. Previously trained rats are placed in plexiglass experimental chambers divided into two sections; a main chamber (10 1/2" x 6 3/4" x 11 7/8" high) and an elevated chamber or shelf (5 7/8" x 6 7/8" x 5 3/4"). A moveable wall, controlled by a motor, determines whether the rat has access to the shelf at any time during the experiment. The experimental chamber also contains a house light and sonalert. A steel grid floor in the main chamber is wired for presentation of electric shock. Each trial consists of a fifteen-second warning tone (conditioned stimulus), continuing for an additional fifteen seconds accompanied by electric shock (unconditioned stimulus). A response (jumping onto the exposed shelf of the upper chamber) occurring during the initial fifteen-second warning tone is considered an avoidance response, while a response occurring during shock delivery is considered an escape response. Trials are presented on a fixed interval schedule of one minute. The session consists of thirty-six trials. Animals are run twice weekly with control sessions always preceding a drug run, and with at least one day intervening. Compounds are administered i.p. or p.o. at appropriate pre-treatment times to a minimum of five rats at each dose level over a range of doses. The following experimental parameters are recorded by computer: (1) the number of avoidance responses, (2) the number of escape responses, and (3) the number of trials in which no response occurred. These data are used to calculate the percent difference from control values previously determined and are presented for visual comparison via a line graph. Response counts are summed over all subjects at a given dose. The number of trials in which rats fail to exhibit an avoidance response (Avoidance Block, AB) is determined at each dose. This number is expressed as a percentage of the total trials. Control performance is arbitrarily assigned a value of 100% for avoidance responding and the dose calculated to produce a 50% block in avoidance responding (AB₅₀) is obtained from a dose-effect regression line fitted by the method of least squares. Potential antipsychotic compounds suppress avoidance responding and increase escape responding. The results for compounds of this invention in this test are presented in Table 3. The results show that compounds of the invention are active intraperitoneally in this test.

Claims: A compound having the formula wherein R¹ and R² are each independently, hydrogen, C₁-C₆ alkyl, C₆-C₁₂ aryl or halo, or R¹ and R² taken together represent -CH₂-, -CH₂-CH₂-, -O-, -NH-, -CH₂-CR³R⁴-, -CO-CR³R⁴-, -CH=CH-S-, =CH-S-CH=, -S-CH=CH-, where the dotted lines in formulae I, V, VI and VIII represent optional double bonds; R³, R⁴, R⁵ and R⁶ are each, independently, hydrogen, C₁-C₆ alkyl, C₆-C₁₂ aryl or halo; R⁷ is 2-pyridinyl, 2-pyrimidinyl, 2-pyrazinyl or 3-pyridazinyl or any of the foregoing R⁷ moieties substituted by C₁-C₆ alkyl, trifluoromethyl, cyano, nitro or halo, with the proviso that when R¹ and R² taken together represent a group of formula IV, then R⁷ is other than substituted or unsubstituted 2-pyridinyl or substituted or unsubstituted 2-pyrimidinyl; Z is -(CH₂) n -, vinylene, -O-, or a group of formula IV; X is C₁-C₄ alkylene, vinylene, O or NH; m is 2 - 5; n is 0 - 4; o is 1 - 3; p is 1 - 4; or a pharmaceutically acceptable salt thereof. A compound as claimed in Claim 1, wherein R⁷ is 2-pyridinyl, 2-pyrimidinyl, halopyrimidin-2-yl, 2-pyrazinyl, halopyrazin-2-yl, 3-pyridazinyl, or halopyridazin-3-yl, and R¹ and R² are as defined in Claim 1 except that R¹ and R² do not represent formula V, R⁶ (if present) is hydrogen and Z (if present) is not vinylene. A compound as claimed in Claim 1, wherein R⁷ is 2-pyrazinyl or 3-pyridazinyl or either of these moieties substituted by C₁-C₆ alkyl, trifluoromethyl, cyano, nitro or halo. A compound as claimed in Claim 1 or Claim 3, wherein R¹ and R² together represent a group of formula V, VI VII or VIII. A compound according to claim 1 which is 3aα,4β,7β,7aα-Hexyahydro-2-[4-[4-(6-chloro-2-pyrazinyl) -1-piperazinyl]butyl]-4,7-epoxy-1,2-benzisothiazol-3 (2H)-one 1,1-dioxide or a pharmaceutically acceptable salt thereof. A compound according to claim 1 which is 3a,4,7,7a-Tetrahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide or a pharmaceutically acceptable salt thereof. A compound according to claim 1 which is selected from the group consisting of 3a,3,7,7a-tetrahydro-2-[4-[4-(2-pyrimidinyl-1-piperazinyl ]butyl]-4,7-ethano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 3a,4,7,7a-tetrahydro-5,6-dimethyl-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a-tetrahydro-5,6-dimethyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a-tetrahydro-4,7-ethano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 4,4a,5,5a,6,6a-hexahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,6-etheno-2H-cyclopropa[f][1,2] benzisothiazol-3(3aH)-one 1,1-dioxide; 2-[4-[4-(6-chloro-2-Pyrazinyl)-1-piperazinyl]butyl]-4,4a,5,5a,6,6a-hexahydro-4,6-etheno-2H-cyclopropa[f] [1,2]-benzisothiazol-3(3aH)-one 1,1-dioxide; 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl] thieno[3,4-d]isothiazol-3(2H)-one 1,1-dioxide and their pharmaceutically acceptable salts. A compound according to claim 1 which is selected from the group consisting of 2-[4-[4-(3-chloro-2-pyrazinyl)-1-piperazinyl]butyl]1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(3-chloro-2-pyrazinyl)-1-piperazinyl]butyl]thieno[3,4-d]isothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(3-Chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a-tetrahydro-5,6-dimethyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a,4,7,7a-tetrahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-3a,4,5,6,7,7a-hexahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-3a, 4,5,6,7,7a-hexahydro-4,7-methano-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; hexahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,6-ethano-2H-cycloprop[f]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; (3aα,4β,7β,7aα)-hexahydro-2-[4-[4-(2-pyrazinyl)-1-piperazinyl]butyl]-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; (3aα,4α,7α,7aα)-2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]hexahydro-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide; 3a,4,4a,6a,7,7a-hexahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4,7-ethenocyclobut[ f ]-1,2-benzisothiazol-3(2H)-one 1,1-dioxide and their pharmaceutically acceptable salts. A pharmaceutical composition comprising a compound as claimed in Claim 2,5,6 or 7 in combination or association with a pharmaceutically acceptable carrier. A pharmaceutical composition comprising a compound as claimed in Claim 1 or 8 in combination or association with a pharmaceutically acceptable carrier. A pharmaceutical composition as claimed in Claim 10 in unit dosage form. A pharmaceutical composition as claimed in Claim 10 in the form of a sterile solution containing other solutes or in the form of tablets or capsules. Claims for the following Contracting States: AT, ES, GR A process for the preparation of a compound having the formula wherein R¹ and R² are each independently, hydrogen, C₁-C₆ alkyl, C₆-C₁₂ -aryl or halo, or R¹ and R² taken together represent -CH₂-, -CH₂-CH₂-, -O-, -NH-, -CH₂-CR³R⁴-, -CO-CR³R⁴-, -CH=CH-S-, =CH-S-CH=, -S-CH=CH- where the dotted lines in formulae I, V, VI and VIII represent optional double bonds; R³, R⁴, R⁵ and R⁶ are each, independently, hydrogen, C₁-C₆ alkyl, aryl or halo; R⁷ is 2-pyridinyl, 2-pyrimidinyl, 2-pyrazinyl or 3-pyridazinyl or any of the foregoing R⁷ moieties substituted by C₁-C₆ alkyl, trifluoromethyl, cyano, nitro or halo, with the proviso that when R¹ and R² taken together represent a group of formula IV, then R⁷ is other than substituted or unsubstituted 2-pyridinyl or substituted or unsubstituted 2-pyrimidinyl; Z is - (CH₂) n -, vinylene, -O-, or a group of formula IV; X is C₁-C₄ alkylene, vinylene, O or NH; m is 2 - 5; n is 0 - 4; o is 1 - 3; p is 1 - 4; or a pharmaceutically acceptable salt thereof; in which (a) a cyclic amine having the formula A (wherein o or R⁷ are as defined above) or a salt thereof is alkylated to introduce the substituted alkyl group having the formula B by reaction with a compound having the formula R⁸-Y (wherein R⁸ is the group having formula B and Y is a leaving group, ) or (b) a cyclic amine having the formula A as defined and illustrated above or a salt thereof is subjected to reductive alkylation with an aldehyde having the formula C (wherein R¹, R², m and the dotted line are as defined (above); or (c) a compound having the formula D (wherein R¹, R² and the dotted line are as defined above) or a salt thereof is reacted with a compound having the formula E₁ or containing the cation E₂ (wherein m, o and R⁷ are as defined above subject to the proviso that in formula E₂ m is 2 to 4 and o is 2 or 3 and Y is a leaving group, for instance a halo atom such as chloro or bromo); or (d) a compound having the formula F wherein R¹, R², R⁷, m, o and the dotted line are as defined above) or a salt thereof is (i) subjected to a Diels-Alder reaction by reaction with a compound having the formula G, H, J, K, L₁ or L₂ (wherein R³, R⁴, R⁵, R⁶, X, Z, P and the dotted line are as defined above), (ii) subjected to epoxidation, (iii) subjected to carbene insertion or (iv) subjected to insertion of a nitrogen residue to form an aziridine of formula N below or a salt thereof; or (e) a compound having the formula M (wherein m, o and R⁷ are as defined above) or a salt thereof is reacted with a suitable nitrogen nucleophile to open the oxirane ring and the resultant intermediate is transformed into an aziridine having the formula N (wherein m, o and R⁷ are as defined above) or a salt thereof; or (f) a compound having the formula F as hereinbefore defined and illustrated or a salt thereof is reacted with a ketene having the formula O=C=CR³R⁴ (wherein R³ and R⁴ are as defined above) to prepare a compound having the formula P (wherein R³, R⁴, m, o and R⁷ are as defined above) or a salt thereof; or (g) a compound having the formula P as hereinbefore defined and illustrated or a salt thereof is reduced to prepare a compound having the formula Q (wherein R³, R⁴, m, o and R⁷ are as defined above) or a salt thereof; or (h) a compound having the formula R (wherein R¹, R², m, o and R⁷ are as defined above and R⁹ is an organosulphonyl group) or a salt thereof is subjected to sulphinic acid elimination; or (j) an ethylenically unsaturated compound according to formula I or a salt thereof is reduced to form a saturated analogue thereof; or (k) a compound having formula I is converted into an acid addition salt thereof by addition of an acid or an acid addition salt of a compound having formula I is subjected to neutralisation to form the compound having formula I. A process as claimed in claim 1, wherein R⁷ is 2-pyrazinyl or 3-pyridazinyl or either of these moieties substituted by C₁-C₆ alkyl, trifluoromethyl, cyano, nitro or halo. A process as claimed in Claim 1 or Claim 2, wherein R¹ and R² together represent a group of formula V, VI, VII or VIII. A process as claimed in claim 1, wherein the compound prepared is 3aα, 4β,7β,7aα-hexahydro-2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-4,7-epoxy-1,2-benzisothiazol-3 (2H)-one 1,1-dioxide or a pharmaceutically acceptable salt thereof. A process as claimed in Claim 1, wherein the compound prepared is 3a,4,7,7a-tetrahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]-4,7-methano-1,2-benzisothiazol-3 (2H)-one 1, 1-dioxide or a pharmaceutically acceptable salt thereof. A process for the preparation of a pharmaceutical composition, which comprises bringing a compound having the formula I as illustrated and defined in Claim 1 into combination or association with a pharmaceutically acceptable carrier. A process as claimed in claim 6, wherein R⁷ is 2-pyrazinyl or 3-pyridazinyl or either of these moieties substituted by lower alkyl, trifluoromethyl, cyano, nitro or halo. A process as claimed in Claim 6 or Claim 7, wherein R¹ and R² together represent a group of formula V, VI, VII or VIII. A process as claimed in Claim 6, wherein 3aα,4β,7β, 7aα-hexahydro-2-[4-[4-(6-chloro-2-pyrazinyl)-1-piperazinyl]butyl]-4,7-epoxy-1,2-benzisothiazol-3(2H)-one 1,1-dioxide or a pharmaceutically acceptable salt thereof is brought into combination or association with a pharmaceutically acceptable carrier. A process as claimed in Claim 6, wherein 3a,4,7,7a-tetrahydro-2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-4, 7-methano-1,2-benzisothiazol-3(2H)-one, 1,1-dioxide or a pharmaceutically acceptable salt thereof is brought into combination or association with a pharmaceutically acceptable carrier.

Inventors: ABOU-GHARBIA, MAGID ABDEL-MEGID, CHILDRESS, SCOTT JULIUS, SCHIEHSER, GUY ALAN
Applicants: AMERICAN HOME PRODUCTS CORPORATION
Application year: 1986
Main classification: C07D417
IPC codes: C07D275, C07D417, C07D513