Catalytic enantioselective Cr-mediated propargylation: application to halichondrin synthesis.
Org Lett
; 11(20): 4520-3, 2009 Oct 15.
Article
em En
| MEDLINE
| ID: mdl-19810761
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.
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2009
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Article