Tert‐ Butyl nitrite promoted visible light induced steric‐hindrance‐regulated concurrent cross‐coupling and regioselective nitration of 3‐alkylidene‐2‐ oxindoles

Abstract

tert‐ butylnitrite (TBN) promoted visible‐light‐induced one‐pot C‐N cross coupling reaction of 3‐alkylidene‐2‐oxindoles with benzene‐1,2‐diamine has been explored. Simultaneously, the indoline motif of 3‐alkylidene‐2‐oxindoles as well as 3‐ylidene oxindoles are regioselectively nitrated at C‐6 position by in‐situ formed NO2 radical. (E)‐3‐(2‐(aryl)‐2‐oxoethylidene)oxindole and (E)‐3‐ylidene oxindole, produce distinct nitrated diastereomeric coupling products, a phenomenon influenced by the steric bulk of the functional group. The experimental findings suggest the potential involvement of a radical pathway in this reaction.