Asymmetric desymmetrization of pseudo-meso 5-hydroxy-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-ones

A novel route to the enantiopure endo-tricyclodecadienone system has been accomplished starting from readily accessible pseudo-meso-5-hydroxy-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one. Desymmetrization using (S)-prolinol or its methyl ether leads to the corresponding enaminones in high yields and with a de of 50%. Complete separation of the diastereomers has been conveniently achieved via their acetates. The absolute stereochemistry of the major diastereomer was determined by single-crystal X-ray diffraction analysis. Reductive elimination of the chiral auxiliary with lithium aluminum hydride affords optically pure parent tricyclodecadienone in good overall yield.