Selective Deoxygenation of Unsaturated Carbohydrates with Pd(0)/Ph2SiH2/ZnCl2. Total Synthesis of (+)-(S,S)-(6-Methyltetrahydropyran-2-yl)acetic Acid

Article abstract of DOI:10.1021/jo00251a011

Highly chemoselective reductive cleavage of allylic acetates of 1,2- and 2,3-unsaturated monosaccharides was achieved by a three-component reducing system comprised of diphenylsilane, a soluble palladium(0) catalyst, and catalytic amounts of zinc chloride.It was demonstrated that hydride substitution proceeds with absolute inversion of configuration at the carbon, implying that hydride is initially transferred to palladium and from there to the allylic ligand.The usefulness of the new chiral building blocks thus formed was demonstrated by the total synthesis of the civet constituent, (+)-(2S,6S)-cis-(6-methyltetrahydropyran-2-yl)acetic acid and its 2R,6S-trans isomer.