Studies on s-cis/s-trans preference of acyclic alpha,beta-unsaturated esters: reactions, supersonic jet spectroscopy, NOEs, and x-ray analysis

S-cis conformation is the major orientation in the addition reaction of alpha,beta-unsaturated esters with metal amides. Supersonic jet spectroscopic analysis of methyl cinnamate reveals equal populations of s-cis and s-trans conformers at room temperature. NOE experiments of methyl cinnamate reveal the dominance of the s-cis form in solution at low temperature. X-ray analyses of enoates reveal the preference of the s-cis form in the solid state.