Abstract

How can you catalyse the 1,6-conjugate addition of carbon-nucleophiles to acyclic, achiral 2,4-dienals enantioselectively? This question raises two key issues in catalysis: how to favour 1,6-regioisomers (over 1,4- or 1,2-adducts) and how to achieve a stereodifferentiating event at a weakly electrophilic site. While these issues are challenging enough, this very feat has been achieved by the Jørgensen group under remote iminium-stereocontrol, whereby δ-alkyl dienals can react with olefinic lactones in the presence of the Jørgensen-Hayashi catalyst to give 1,6-adducts exclusively.