Enantioselective Twofold C-H Annulation of Formamides and Alkynes without Built-in Chelating Groups

Abstract

Twofold C-H annulation of readily available formamides and alkynes without built-in chelating groups was achieved. Ni-Al bimetallic catalysis enabled by a bulky BINOL-derived chiral secondary phosphine oxide (SPO) ligand proved to be critical for high reactivity and high selectivity. This reaction uses readily available formamides as starting materials and provides a concise synthetic pathway to a broad range of chiral ferrocenes in 40-98 % yield and 93-99 % ee.

Keywords: aluminum; annulation; ferrocenes; formamides; nickel.