2-Methylbenzenesulfonic acid hydrate → methyl 1-(4-aminosulfonylphenyl)methylene-5-methoxy-2-methyl-1H-3-indenylacetate

Participants

Reaction Steps

A solution of the E acid 3a (950 mg) and toluenesulfonic acid monohydrate (200 mg) in methanol (60 ml) was refluxed for 1-2 hours. The solution was filtered and the filtrate was concentrated to 30 ml. After cooling at 0° to 5° for 1 hour, the crystals were collected and dried. The crude ester was recrystallized from acetonitrile to give the pure E methyl 1-(4-aminosulfonylphenyl)methylene-5-methoxy-2-methyl-1H-3-indenylacetate 5a (850 mg, 86%): m.p. 169.5°-171.0° C.

Provenance & Evidence