Asymmetric Henry Reaction Catalyzed by Novel Chiral Bioxazolines from Tartaric Acid
摘要:
Novel C-2-symmetric chiral bioxazolines were synthesized in good yields by the fusion of optically active acids with a tartaric acid derivative. Complexes of these products with copper(II) acetate monohydrate were found to be excellent catalysts for the Henry reaction, giving various nitro alcohols in very good yields and up to 84% enantiomeric excess. Although only five-membered chelation is possible with these ligands, they give better enantioselectivities than other bioxazoline ligands that undergo similar coordination.
Enantioselective fluorination of β-ketoesters using tartrate derived bidentate bioxazoline-Cu(II) complexes
摘要:
Enantioselective fluorination of aliphatic cyclic and acyclic beta-ketoesters was achieved in excellent yield (up to 98%) with moderate to good enantioselectivities (up to 86% ee) using tartrate derived bidentate bioxazoline-Cu(II) complexes. This is the first report of a bioxazoline which forms a 5-membered chelate inducing enantioselectivity in the asymmetric fluorination of beta-ketoesters. (C) 2013 Elsevier Ltd. All rights reserved.