Stereospecific Syntheses of the Lignans: 2-S-(3,4-Dimethoxybenzyl)-3-R-(3,4,5-trimethoxybenzyl) Butyrolactone, and Its Positional Isomeric Lactone

Abstract

A short, versatile and stereospecific synthesis of two lignans 1 and 2, was achieved in 40% overall yield. Our strategy was based in the use of amino acids as chiral and readily available starting materials. Stereocontroled transformation of amino acids to chiral organic phosphonates gave the key intermediate of the synthetic sequence. A Horner-Wadsworth-Emmons (HWE) reaction followed by selective reduction and stereospecific hydrogenation in the last step resulted in the title compounds with the desired absolute stereochemistry.