Organocatalytic Gram-Scale Synthesis and Alkylation of Heteroaryl and Electron-Rich Aryl α-Substituted γ-Lactones

Abstract

The synthesis of γ-lactones α-substituted with heterocycles and electron-rich aromatic rings is described. The method, based on a sequence involving an organocatalytic addition of boronic acid to the 5-hydroxyfuran-2(5H)-one, followed by reduction and lactonization, gives access to broad range of γ-lactones on a gram scale. Among these, γ-lactones bearing a benzofuran, a benzothiophene, and an indole ring were alkylated in mild catalytic conditions to construct α-quaternary stereocenters. Interesting mild oxidation reaction, using molecular oxygen, was also highlighted during this study.