Asymmetric synthesis of new γ-butenolides via organocatalyzed epoxidation of chalconesElectronic supplementary information (ESI) available: Experimental details and NMR spectra. See DOI: 10.1039/c7ob00165g

γ-Butenolides have been recognized as an important structural framework in a number of natural products and medicinally important agents. In this work we describe a new metal-free sequential strategy for the asymmetric synthesis of substituted γ-butenolides having epoxychalcones as the advanced intermediate. Using the optimized reaction conditions, we were able to carry out the three-step sequence, epoxidation, olefination and hydrolysis, with only one single chromatographic purification of the final product, furnishing new enantiomerically enriched γ-butenolides in moderate overall yield and good enantiomeric excess. A greener three-step sequence, with only one single chromatographic purification, afforded γ-butenolides in moderate overall yield and high enantiomeric excess.