Palladium-Catalyzed Enantioselective γ-Arylation of β,γ-Unsaturated Butenolides

Abstract

γ-Butenolide and γ-butyrolactone scaffolds are two types of important core structures in numerous natural products and bioactive targets. However, methods to construct the chiral quaternary arylated γ-butenolide are rarely explored. We herein report an efficient Pd-catalyzed enantioselective γ-arylation of β,γ-unsaturated butenolides with aryl bromides, which shows high γ-selectivity, good functional group tolerance and excellent enantioselectivity. Notably, this protocol also allows for facile construction of tricyclic tetrahydroindolines and tetrahydroisoquinolinones in one step. DFT calculations are consistent with the experimental results, suggesting that the γ-arylation is favoured over the α-arylation. Finally, this method is applied to the rapid synthesis of natural product (R)-(+)-boivinianin A.

Keywords: Arylation; Asymmetric Synthesis; Butenolide; Butyrolactone; Palladium Catalysis.