The influence of α-coordinating groups of aldehydes on <i>E</i>/<i>Z</i>-selectivity and the use of quaternary ammonium counter ions for enhanced <i>E</i>-selectivity in the Julia–Kocienski reaction
Modified reaction conditions for improved E-selectivity of olefins in the Julia–Kocienski reaction of aldehydes having α-coordinating substituents are demonstrated. The chelating groups in aldehydes are expected to stabilize the syn-transition state with metal ions, whereas the weakly coordinating quaternary ammonium ions are devoid of all possible chelating interactions to enhance E-selectivity. A