Nucleophilic addition reactions of 2-nitro-1-(phenylsulfonyl)indole. A new synthesis of 3-substituted-2-nitroindoles

Abstract

2-Nitro-1-(phenylsulfonyl)indole (1) undergoes nucleophilic addition reactions with the enolates of diethyl malonate and cyclohexanone, lithium dimethylcuprate, and indole anion to afford the corresponding 3-substituted-2-nitroindoles (4–6, 8, 9) in low to high yields. Reaction of 1-(phenylsulfonyl)-2-(trialkylstannyl)indoles 13 and 14 with tetranitromethane affords the novel isoxazolo[5,4-b]indole 15 via a 1,3-dipolar cycloaddition reaction with in situ generated nitro formonitrile oxide (19).