Catalytic Asymmetric Diels-Alder Reaction of Quinone Imine Ketals: A Site-Divergent Approach

The catalytic asymmetric Diels–Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl‐substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels–Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3‐alkyl quinone imine ketals from the inherently favored unsubstituted CC bond to the disfavored alkyl‐substituted CC bond. Wahl des ungünstigen Angebots: Axial‐chirale Dicarbonsäuren katalysieren die Diels‐Alder‐Reaktion von Chinoniminketalen mit Diencarbamaten. Dabei kann das Reaktionszentrum in unsymmetrischen 3‐Alkylchinoniminketalen von der inhärent begünstigten, unsubstituierten CC‐Bindung zur nicht begünstigten, alkylsubstituierten CC‐Bindung umgelenkt werden.