BIMP Catalyzed 1,3-Prototropic Shift for the Highly Enantioselective Synthesis of Conjugated Cyclohexenones

A bifunctional iminophosphorane (BIMP) catalyzed enantioselective synthesis of α,β-unsaturated cyclohexenones via a facially selective 1,3-prototropic shift of β,γ-unsaturated prochiral isomers, under mild reaction conditions and in short reaction times, on a range of structurally diverse substrates, is reported. α,β-Unsaturated cyclohexenone products primed for downstream derivatisation were obtained in high yields (up to 99%) and consistently high enantioselectivity (up to 99% ee). In-depth studies into the reaction mechanism and origins of enantioselectivity, including multivariate linear regression of TS energy, were carried out computationally on the catalytic system and the obtained data was found to be in good agreement with experimental findings.