Base Catalysed Diastereoselective Dimerization of α- and β-Angelica Lactones

Abstract

Unsaturated -lactones represent an important class of molecules which can be further utilized for the synthesis of biologically active drug molecules, natural products like alkaloids and bio-fuels. − and −angelica lactones collectively termed as butenolides are two well known molecules of this class and present in many biologically active molecules. −angelica lactone can be easily converted in to its stabilized form −angelica lactones. Here in this work, we are utilizing −angelica lactone for the dimerization in the presence of inorganic base (K2CO3) and interestingly under the solvent free conditions, we obtained homodimerized product in yield 53% with diastereoselectivity 30:70 dr. Surprisingly, with solvent the homodimerized product selectivity was switched into opposite diastereomer as a major isomer (up to 81% yield, up to 92:8 dr). These different dimers further can be utilized for the bio-fuels applications and biologically active drug molecules synthesis.