Hydrochloric Acid → 6-chloro-2,3-dihydro-3-oxo-2-(2-pyridinylmethyl)-1H-isoindole-5-sulfonamide

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반응 단계

Tin-Hydrochloric Acid Reduction of 6-Chloro-2,3-dihydro-1,3-dioxo-2-(2-pyridinylmethyl)-1H-isoindole-5-sulfonamide. A mixture of the above part (a) 1,3-dioxoisoindole (18 g., 0.051 mole), 120 ml. of methanol and 60 ml. of concentrated hydrochloric acid was heated with 30 mesh granulated tin metal added as indicated: 15 g. at 65°-70° for 6 hr., then 8 g. at 60°-65° for 16 hr. and finally 6 g. at 70°-75° for a 7 hr. period. The reaction mixture is cooled, filtered and concentrated to about 60 ml. volume. Addition of about 60 ml. of methanol to the concentrated mixture provided on standing 10 g., of a tin salt complex. This material was further purified by stirring with 1 liter of 50% methanol and 20 ml. of 1N hydrochloric acid while slowly introducing a gaseous stream of hydrogen sulfide (H2S) during a 1 hr. period at 45°-50°. The mixture is stirred at 40°-45° for 16 hr. and then concentrated slightly to remove excess H2S. Activated charcoal was added and the mixture filtered. Concentration of the filtrate to about 50 ml. and dilution with 1 ml. of 6N hydrochloric acid and cooling yielded 2.2 g. (12%) of white solid. Crystallization from aqueous methanol afforded analytically pure 6-chloro-2,3-dihydro-3-oxo-2-(2-pyridinylmethyl)-1H-isoindole-5-sulfonamide as the hydrochloride salt, m.p. 264°-266°.

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