Rhodium-Catalyzed Direct C7 Alkynylation of Indolines

An efficient rhodium(III)-catalyzed direct C7 alkynylation of indoline C-H bonds with the alkynylated hypervalent iodine reagents has been developed. This reaction proceeds smoothly under mild conditions over a wide structural scope with high site-selectivity and excellent functional-group tolerance. N-Acetyl as well as other N-acyls served as effective directing groups (DG). This procedure allows for the synthesis of a variety of 7-alkynyl-substituted indolines in good to excellent yield. More significantly, C7-alkynylated indoles through further transformations have been successfully accessed.