title: Catalytic enantioselective Cr-mediated propargylation: application to halichondrin synthesis.
abstract: A catalytic enantioselective propargylation in the presence of 10 mol % of Cr catalyst prepared from Cr(III) bromide and (R)-sulfonamide E furnishes homopropargyl alcohol 8 in 78% yield with 90% ee. Coupled with the workup based on Amano-lipase, this method provides a practical synthesis of optically pure 8 on a multigram scale. With maintenance of its optical purity, 8 has been converted to 1b, the C14-C19 building block of halichondrins and E7389, in two steps.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
authors.forename: Songbai
authors.initials: S
authors.lastname: Liu
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Kim
authors.forename: Cheng-Guo
authors.initials: CG
authors.lastname: Dong
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Kishi
mesh_terms: D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D004988:Ethers, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry*; D018942:Macrolides; D013237:Stereoisomerism; D013379:Substrate Specificity; D000095662:Polyether Polyketides
chemical_list: D002857:Chromium; D004988:Ethers, Cyclic; D018942:Macrolides; C070519:halichondrin B; D000095662:Polyether Polyketides