What's Up With BINOL and BINAP?

Abstract

From the ACS meeting Two of the most widely used chiral ligands for asymmetric catalysis are BINOL (2,2′-dihydroxy-1,1′-binaphthyl) and BINAP [2,2′-bis(diphenylphosphino)-1,1′-binaphthyl]. Researchers continue to tweak these ligands to fine-tune their properties. Among them are Andrei K. Yudin, an assistant professor of chemistry at the University of Toronto, and Lin Pu, an associate professor of chemistry at the University of Virginia. Both spoke last month at a symposium sponsored by the Division of Organic Chemistry. Yudin is developing a new class of chiral ligands based on fluorinated BINOLs. Work in his lab shows that substitution of some BINOL hydrogens with fluorines confers stability, affects coordination preferences, and leads to enantioselective catalysts with quite different reactivities. Yudin explains that the fluorinated-BINOL project originated from an old and underutilized finding that benzene (C 6 H 6 ) and perfluorobenzene (C 6 F 6 ) form tight interpenetrating stacks. The stacking inte...