Catalytic enantioselective Cr-mediated propargylation: application to halichondrin synthesis.
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.
Liu
Songbai
S
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Kim
Joseph T
JT
Dong
Cheng-Guo
CG
Kishi
Yoshito
Y
D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D004988:Ethers, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry*; D018942:Macrolides; D013237:Stereoisomerism; D013379:Substrate Specificity; D000095662:Polyether Polyketides
D002857:Chromium; D004988:Ethers, Cyclic; D018942:Macrolides; C070519:halichondrin B; D000095662:Polyether Polyketides