OPTICALLY PURE DIHYDROXY GAMMA-ALKYLATED GAMMA-BUTYROLACTONES STARTING FROM L-TARTARIC ACID - APPLICATION TO FORMAL AND TOTAL SYNTHESES OF NATURAL-PRODUCTS

A general and efficient preparation of epimeric optically pure gamma-b utyrolactones 2 and 3 is described starting from L-tartaric acid (1). These lactones are well-known to be important building blocks in the s yntheses of natural products. L-Tartaric acid (1) was transformed into carbonylated chirons (ketones 4 and aldehyde 5). These chirons, when submitted to highly stereoselective reactions (reduction or organometa llic addition), led to epimeric dihydroxy gamma-butyrolactones 2 and 3 after lactonization and deprotection steps. The resulting optically p ure lactones are precursors of biological compounds and have allowed a total synthesis of L-biopterin and formal syntheses of quercus lacton e, dodecanolactone, avenaciolide, and tetrahydrocerulenin.