Asymmetric desymmetrization of a pseudo-meso endo-tricyclo[5.2.1.0(2,6)]deca-4,8-dien-3-one by chiral amines

A novel route to the enantiopure endo-tricyclodecadienone system has been realized starting from the readily accessible pseudo-meso-5-hydroxy-endo-tricyclo[5.2.1.0(2,6)]deca-4,8-dien-3-one 4. Dynamic kinetic resolution of (+/-)-4 using (S)-prolinol or its methyl ether leads to the corresponding enaminones 6b,c in high yields and with a de of 50%. Complete separation of the diastereomers of 6b is conveniently accomplished via their acetates. The absolute stereochemistry of the major diastereomer was shown to be ent-6b. Reductive elimination of the chiral auxiliary in ent-6b with lithium aluminum hydride affords optically pure parent tricyclodecadienone (+)-1 (X=H) in good overall yield. Copyright (C) 1996 Elsevier Science Ltd.