Asymmetric synthesis of tricyclic-cyclobutane by means of enantioselective deprotonation and intramolecular Michael–aldol reaction

We have demonstrated the syntheses of enantiomerically enriched tricyclo[4.2.1.03,8]nonanes from Cs symmetric cyclohexanones by means of enantioselective deprotonation, followed by an intramolecular Michael–aldol reaction. The asymmetric deprotonation was achieved in up to 79% ee and the following Michael–aldol reaction gave the corresponding tricyclononanes with almost the same optical purity.