Enantioselective conjugate radical addition reactions mediated by chiral Lewis acid complexes of ( R, R)-4,6-dibenzofurandiyl-2,2′-bis(4-phenyloxazoline) (DBFOX/Ph)

Abstract

A high-yielding synthesis (50% overall yield) of tridentate bisoxazoline ligand ( R, R)-4,6-dibenzofurandiyl-2,2′-bis(4-phenyloxazoline) (DBFOX/Ph) was developed. DBFOX/Ph was subsequently tested in enantioselective conjugate radical additions onto 3-(3-phenyl-2-propenoyl)-2-oxazolidinone. Two dozen Lewis acids were evaluated, and Mg(ClO 4) 2 emerged as the best Lewis acid in terms of yield and enantioselectivity (100% yield, 75.4% ee ( S)).