Photoinduced, Chemoselective γ-Alkylation of 2-Silyloxyfurans With α-Bromoketones: A Rapid Entry to Chiral ε-Keto-γ-Butenolides.

γ-Butenolides are widespread structural motifs found in many natural and unnatural products which display an impressive range of biological activities. Among them, ε-keto-γ-butenolides represent underestimated butenolide frameworks, which could serve as valuable platforms to build complex structures, for example, heterobicyclic derivatives. Quite unexpectedly, despite the apparent simplicity of their structures, efficient synthetic methodologies enabling the construction of chiral, ε-keto-γ-butenolide architectures are quite underdeveloped. In this context, herein we present a novel, photoinduced regio- and chemoselective γ-alkylation of 2-silyloxyfurans with 2-bromoketones providing a practical access to ε-ketobutenolide scaffolds in racemic format, in one single step and high yields. The usefulness of these products as starting materials to build chiral, fused-heterobicycle lactone derivatives was demonstrated by the implementation of a two-step strategy which successfully delivered unprecedented phenyltetrahydrofuro[3,2-b]furan-2(3H)-one and tetrahydrofuro[3,2-c]pyridazin-6(1H)-one chemotypes.