Configurational Instability of α-Alkenyl and α-Alkynyl Vinyllithiums. Syntheses of Stereodefined 2-Alkyl-1-en-3-ynes

Article abstract of DOI:10.1021/jo00243a056

Metal-halogen exchange of either (Z)-enynyl bromides or (Z)-dienyl bromides by sec-BuLi produces vinyllithiums that are configurationally stable only at temperatures below -120 deg C and -78 deg C, respectively.Allylation of (Z)-enynylalanates with allyl bromide or methylation of (Z)-enynyl bromides with CH3MgI and Fe(acac)3 catalyst furnishes the corresponding 2-alkyl-1-en-3-ynes.