Highly Diastereoselective Conjugate Addition of Carbon Nucleophiles to a Chiral Oxygenated alpha,beta-Unsaturated delta-Lactone. A Straightforward Synthesis of Functionalized Branched-Chain L-Sugars

Highly functionalized chiral, enantiomerically pure, molecules are useful intermediates for the EPC synthesis of natural products and pharmacologically active compounds. The stereocontrolled synthesis of these chiral building blocks is an important objective in organic chemistry. Stereocontrolled carbon-carbon bond formation is a major goal in modern synthetic methodology. Conjugate addition of carbon nucleophiles is an important tool to achieve this objective. In this paper, we report our results on the highly diastereoselective conjugate addition of both dialkyl cuprates and soft nucleophiles to the readily available8a chiral alpha, beta-unsaturated delta-lactone