Cu‐Catalyzed Allylic C─H Arylation of 3‐Phospholene Oxides with Triarylboroxines

Abstract A copper‐catalyzed oxidative allylic C─H arylation of 3,4‐diaryl‐3‐phospholene 1‐oxide derivatives with triarylboroxines is presented. Under the optimized conditions, the reaction displayed a broad compatibility for both phospholene and boroxine substrates, affording 2‐monoarylated and 2,5‐diarylated phosphole compounds in high overall yield (up to 74%), with monoarylated products as major products in moderate to moderately high yields (up to 58%). The scalability of the method was demonstrated by performing the reaction at a gram‐scale level. In addition, the versatile diversification of the products was also exemplified. Consequently, the method provides a new route for the diverse synthesis of structurally novel and potentially useful 2,3,4‐triaryl‐substituted phosphole derivatives and, moreover, enriches the methodology for allylic C─H functionalization.