Chiral triflate technology: An efficient tool for the construction of biologically interesting natural products in optically pure forms

The chiral building block approach to enantiomerically pure compound synthe sis is known as "chiral pool method" and extensively employed for the synth esis of biologically interesting natural products. In spite of its great sy nthetic utility, frequently it becomes a serious problem to elaborate the s ide chain on the carbon center bearing a beta-oxygen functionality. However , because of the electron-withdrawing nature of beta-oxygen it is generally accepted that alkylation through nucleophilic displacement reaction is not so easy. In order to overcome this difficulty we have designed to use the trifluoromethanesulfonates (triflates) as extremely reactive substrates for the required carbon-carbon bond-forming reaction. That is, the alkylation of chiral triflate derivatives with Grignard or oraganolithium reagents pro vides a new rapid means for natural product synthesis and the method is ter med as "chiral triflate technology". In this article, total syntheses of ()-exo-brevicomin, L-factor, the cyclohexyl fragment of FK-506, (+)-diolmyci n A2, (+)-panaxacol, renin inhibitor, and AI-77-B starting from L- or D-tar taric acid or D-ribose as a chiral source are described.