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

Chirality. 2009 Jan;21(1):239-44. doi: 10.1002/chir.20613.


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 beta-nitro alcohols in excellent yields and enantiomeric excesses up to 86%.