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.
We present herein the first oxidation of enynylboronates for the synthesis of γ-lactones, including spiro-, and fused-butanolides as well as butenolides that are prevalent in nature products and bioactive molecules. The asymmetric version of this oxidation was also achieved in the presence of chiral ketone and Oxone. This process successively involves the oxidation of C(sp)−B bond, the epoxidation