Synthesis of Optically Active, Cyclic a-Hydroxy Ketones and 1,2-Diketones from Verbenone Epoxide

The reactivity of verbenone epoxide (5), a terpenoid from the pinane series, towards different aliphatic and aromatic aldehydes in the presence of natural montmorillonite (askanite-bentonite) clay has been studied. A series of mechanistically different transformations afforded a number of new, optically active, polyfunctional compounds (7, 8, 10-14, 16). These products are potentially interesting synthons in asymmetric synthesis.