Rh(Ⅲ)- and Ir(Ⅲ)-Catalyzed C-H Alkynylation of Arenes under Chelation Assistance

摘要

An efficient Rh(Ⅲ)- and Ir(Ⅲ)-catalyzed, chelation- assisted C-H alkynylation of a broad scope of (hetero)arenes has been developed using hypervalent iodine-alkyne reagents. Hetero- cycles, N-methoxy imines, azomethine imines, secondary carbox- amides, azo compounds, N-nitrosoamines, and nitrones are viable directing groups to entail ortho C-H alkynylation. The reaction proceeded under mild conditions and with controllable mono- and dialkynylation selectivity when both mono- and dialkynylation was observed. Rh(Ⅲ) and Ir(Ⅲ) catalysts exhibited complementary substrate scope in this reaction. The synthetic applications of the coupled products have been demonstrated in subsequent derivatiza- tion reactions. Some mechanistic studies have been conducted, and two Rh(Ⅲ) complexes have been established as key reaction intermediates. The current C-H alkynylation system complements those previously reported under gold or palladium catalysis using hypervalent iodine reagents.