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Synlett 1992; 1992(8): 626-628
DOI: 10.1055/s-1992-21434
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Synthesis of (E)-1-Alkenylalkylborinic Esters and Their Ready Conversion into Conjugated (E)-Alkenones

Herbert C. Brown* , Verinder K. Mahindroo
  • *H. C. Brown and R. B. Wetherill Laboratories of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
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Publication Date:
08 March 2002 (online)

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(E)-1-Alkenylalkylborinic esters, easily prepared by the reaction of (E)-1-alkenylboronic esters with alkyllithiums followed by treatment with hydrogen chloride in diethyl ether, react smoothly with α,α-dichloromethyl methyl ether and lithium tert-butoxide (the DCME reaction). Oxidation of the organoborane intermediates with hydrogen peroxide-sodium acetate or trimethylamine oxide produces the corresponding conjugated (E)-alkenones stereoselectively in good yields. This is the first report of the application of the DCME reaction to alkenylboron substrates and expands the scope of this reaction. This methodology has successfully been extended for the enantioselective synthesis of (R)-(-)-trans-3-methyldec-5-en-4-one (19) in ≥ 99% enantiomeric excess.