Electrochemical oxidative intramolecular annulation of aryl phosphine compounds: an efficient approach for synthesizing π-conjugated phosphonium salts

Abstract

A practical and efficient electrochemical approach for the synthesis of π-conjugated phosphonium salts via intramolecular annulation and the construction of the C–P bond is developed. This reaction proceeded under catalyst- and adscititious oxidant-free conditions at room temperature. A series of substituted π-conjugated phosphonium salt products were obtained with good functional group tolerance and yields. A gram-scale reaction was performed to demonstrate the potential of the protocol for practical applications. Preliminary mechanistic studies indicate that free radicals are thought to be involved in this process.