Enantiocontrolled route to natural products using chiral equivalents of cyclopentenone and cyclohexenone
Efficient preparation of two tricyclic dienones, (1) and (2), in both enantiomeric forms has been developed by employing lipase-mediated resolution. A variety of natural products have been synthesized in enantiocontrolled manners by utilizing the former as a chiral equivalent of 2- cyclopentenone (as well as cyclopentadienone) and the latter as a chiral equivalent of 2-cyclohexenone (as well as 2,5-cyclohexadienone). Enantiocontrolled functionalization of cyclopentane and cyclohexane derivatives is one of the most important subjects in the synthesis of optically active materials. In this regard the enantiotopical preparation of two tricyclic dienones 1 and 2 was investigated with intent to use the former as a chiral equivalent of cyclopentenone (as well as cyclopentadienone) and the latter as a chiral equivalent of cyclohexenone (as well as 2,5-~yclohexadienone) in the chiral synthesis of natural products. Because of their biased framework and thermal susceptibility, they allowed highly stereoselective functionalization and generation of the olefin functionality which led to enantiocontrolled synthesis of a variety of natural products.