C,O-Chelated BINOL/Gold(III) complexes : synthesis and catalysis with tunable product profiles

Abstract

Unprecedented stable BINOL/gold(III) complexes, adopting a novel C,O-chelation mode, were synthesized by a modular approach through combination of 1,1′-binaphthalene-2,2′-diols (BINOLs) and cyclometalated gold(III) dichloride complexes [(C^N)AuCl2]. X-ray crystallographic analysis revealed that the bidentate BINOL ligands tautomerized and bonded to the AuIII atom through C,O-chelation to form a five-membered ring instead of the conventional O,O′-chelation giving a seven-membered ring. These gold(III) complexes catalyzed acetalization/cycloisomerization and carboalkoxylation of ortho-alkynylbenzaldehydes with trialkyl orthoformates.