title: Effect of additives on the stereochemical integrity and reactivity of alpha-alkoxycarbonyl alkenylcopper intermediates. Optimal conditions for the synthesis of isomerically pure tetrasubstituted alkenes.
abstract: A systematic study on the effect of additives on the isomerizability of 1-alkoxycarbonyl alkenylcopper(I) intermediates revealed that the lithium chelator 12-crown-4 is significantly more efficient than HMPA at retarding isomerization. On the other hand, 12-crown-4 alone is unable to promote effective coupling with alkyl halides. The combination of 12-crown-4 and a reduced amount of HMPA, however, led to an improved procedure for the preparation of useful, isomerically pure tetrasubstituted alkenes such as allylation reagents and skipped dienes.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Na
authors.initials: N
authors.lastname: Zhu
authors.forename: Dennis G
authors.initials: DG
authors.lastname: Hall