Studies on s-Cis/s-Trans Preference of Acyclic .alpha.,.beta.-Unsaturated Esters. Reactions, Supersonic Jet Spectroscopy, NOEs, and X-ray Analysis

TLDR: The s-cis/s-trans preference of acyclic α, β-unsaturated esters has been studied by their reactions to elucidate the preference in the transition state and by supersonic jet spectroscopy, NOE experiments, and X-ray analysis to clarify the preference as discussed by the authors.

Abstract: The s-cis/s-trans preference of acyclic α,β-unsaturated esters has been studied by their reactions to elucidate the preference in the transition state and by supersonic jet spectroscopy, NOE experiments, and X-ray analysis to clarify the preference in the ground state. It has been rudely accepted that enoate-Lewis acid complexes prefer the s-trans conformation not only in the ground state but also in the transition state of the reactions involving those complexes. The conjugate addition of metal amides to uncomplexed enoates proceeds predominantly through the s-cis conformation, and most organocopper conjugate additions in the absence of Lewis acids or related metal salts take place preferentially in the s-cis conformation