INTERMEDIATES FOR THE PRODUCTION OF 2-SUBSTITUTED PHENYL-4,5,6,7-TETRAHYDRO-2H-ISOINDOLE-1,3-DIONES

Abstract: 2-(4-Chloro-3-hydrothiophenyl)-4,5,6,7-tetrahydro-2H-­ isoindole-1,3-dione and 2-Chloro-5-aminothiophenol are useful as intermediates for the production of herbicidal 2-substituted phenyl-4,5,6,7-tetrahydro-2H-­ isoindole-1,3-diones.

Description: The present invention relates to intermediate compounds for the production of 2-substituted phenyl-4,5,6,7-tetrahydro-2H-isoindole-1,3-diones (hereinafter referred to as "isoindole(s)"). These intermediate compounds are: 2-(4-Chloro-3-mercaptophenyl)-4,5,6,7-tetrahydro-2H-isoindole-1,3-dione and 2-Chloro-5-aminothiophenol. The parent application EP-B-142648 to the present divisional application relates 2-substituted phenyl-4,5,6,7-tetrahydro-2H-isoindole-1,3-diones and their production and use. The said isoindoles are representable by the formula: wherein R₁ is a hydrogen atom, a fluorine atom or a methyl group and R₂ is a C₁-C₃ alkyl group, a C₁-C₅ alkoxy group, a chloro (C₂-C₄) alkoxy group, a dichloro (C₂-C₄) alkoxy group, a cyclo (C₃-C₇) alkoxy group, a phenoxy group, a C₁-C₅ alkylthio group or a di (C₁-C₅) alkylamino group. The isoindoles (I) show a strong herbicidal activity against a wide variety of weeds. The isoindoles (I) are obtainable by reacting 2-(4-chloro-3-mercaptophenyl)-4,5,6,7-tetrahydro-2H-isoindole-1,3-dione with a compound of the formula: wherein R₁ and R₂ are each as defined above and Y is a chlorine atom, a bromine atom or an iodine atom. The starting 2-(4-chloro-3-mercaptophenyl)-4,5,6,7-tetrahydro-2H-isoindole-1,3-dione is obtainable by reacting 2-chloro-5-aminothiophenol with 1 to 3 equivalents of 3,4,5,6-tetrahydrophthalic anhydride in a solvent at a temperature of 90 to 120°C for 1 to 24 hours. As the solvent, there may be employed aliphatic hydrocarbons (e.g hexane, ligroin), aromatic hydrocarbons (e.g. benzene, toluene, xylene), ethers (e.g. diisopropyl ether, dioxane, diethylene glycol dimetyl ether), aliphatic acids (e.g. acetic acid, propionic acid), water, or a mixture thereof. After completion of the reaction, the reaction mixture is subjected to ordinary post-treatment such as extraction, condensation or precipitation. The thus obtained product may be, if necessary, purified by a per se conventional procedure such as column chromatography or recrystallization. A typical example for production of 2-(4-chloro-3-mercaptophenyl)-4,5,6,7-tetrahydro-2H-isoindole-1,3-dione is as follows: Example 1 21.1 g 2-Chloro-5-aminobenzenethiol and 20.4 g tetrahydrophthalic anhydride were dissolved in 130 ml acetic acid, and the resultant mixture was heated at 100 to 110°C for 1 hour while stirring. The reaction mixture was allowed to cool and diluted with water. The precipitated crystals were collected by filtration and washed with ethanol to give 28.2 g of 2-(4-chloro-3-mercaptophenyl)-4,5,6,7-tetrahydro-2H-isoindole-1,3-dione; m.p., 153 -155°C. 2-Chloro-5-aminothiophenol may be produced by reacting 2-chloro-5-nitrobenzenesulfonyl chloride with stannous chloride and hydrochloric acid or with zinc and hydrochloric acid or sulfuric acid at a temperature of 40 to 100°C. The amount of the stannous chloride or zinc is usually from 6 to 10 equivalents to 2-chloro-5-nitrobenzenesulfonyl chloride. After completion of the reaction, the reaction mixture is subjected to post-treatment, for instance, addition of conc. hydrochloric acid and collection of the precipitate. If necessary, the collected product may be further purified by a per se conventional procedure such as chromatography or recrystallization. A typical example for production of 2-chloro-5-aminothiophenol is as follows: Example 2 A solution of 152.5 g anhydrous stannous chloride in 150 ml conc. hydrochloric acid was cooled to 0°C, and 34.3 g 2-chloro-5-nitrobenzenesulfonyl chloride were added thereto while stirring. The resultant mixture was heated at 100°C for 15 minutes while stirring, followed by being allowed to stand. 230 ml conc. hydrochloric acid were added to the reaction mixture. The precipitated crystals were collected by filtration, neutralized with a 4% aqueous sodium carbonate solution and extracted with ethyl acetate. The organic layer was dried and concentrated to give 25.0 g of 2-chloro-5-aminothiophenol; m.p., 68.3°C.

Claims: 2-(4-Chloro-3-mercaptophenyl)-4,5,6,7-tetrahydro-2H-isoindole-1,3-dione. 2-Chloro-5-aminothiophenol.

Inventors: HAGA, TORU, HASHIMOTO, SHUNICHI, NAGANO, EIKI, YOSHIDA, RYO
Applicants: SUMITOMO CHEMICAL COMPANY, LIMITED
Application year: 1984
Main classification: C07D209
IPC codes: A01N37, C07D209, A01N39, A01N43