Synthesis of chiral butenolides using amino-thiocarbamate-catalyzed asymmetric bromolactonization
摘要:
The asymmetric cyclization of 4,4-disubstituted 3-butenoic acids is studied. Amino-thiocarbamates are used as the catalysts and N-bromosuccinimide is used as the stoichiometric halogen source. The resulting gamma-butanolide products are readily converted into the corresponding gamma-butenolides (up to 58% ee) derivatives in one-pot. (C) 2014 Elsevier Ltd. All rights reserved.
A Pd-catalyzed enantioselective γ-selective arylation of β, γ-unsaturated butenolides is reported. The P-chiral phosphine ligand-AntPhos is essential for the observed high γ-selectivity, excellent enantioselectivity and good yields.