New adaptive chiral thiophene ligands for copper-catalyzed asymmetric Henry reaction

A new type of adaptive chiral thiophene‐based ligands 3 has been designed and developed. The synthetic flexibility of the thienyl ring allowed for the preparation of polydendate C2‐symmetric ligands in good yields, carrying simultaneously “hard” as well as “soft” coordinating atoms (i.e., N, S). The coordination attitude of 3 was then tested in the enantioselective base‐free Cu(OAc)2‐catalyzed addition of nitromethane to aromatic aldehydes, leading to the corresponding β‐nitro alcohols in excellent yields and enantiomeric excesses up to 86%. Chirality, 2009. © 2008 Wiley‐Liss, Inc.