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

We have demonstrated the syntheses of enantiomerically enriched tricyclo[4.2.1.0(3.8)]nonanes from C-s symmetric cyclohexanones by means of enantio selective 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. (C) 2001 Elsevier Science Ltd. All rights reserved.