METAL-CATALYZED KINETIC RESOLUTION PROCESSES

A large variety of metal-based chiral complexes have been developed in the past twenty five years that allow for the effective catalytic res olution of an impressive range of racemic compounds. After the initial discovery of Ti-catalyzed kinetic resolution of allylic alcohols by S harpless and coworkers in the early eighties, a number of other transf ormations have emerged that may be used for catalytic resolution. Amon gst them are the Ru-catalyzed hydrogenation, the Zr-catalyzed carbomag nesation, the Mn-catalyzed epoxidation, the Cocatalyzed epoxide hydrol ysis, and the Ti-catalyzed reduction of C=N and C=O bonds. Most recent ly, the Mo-catalyzed ring-closing metathesis has been utilized to cata lytically resolve organic molecules in an efficient manner. This artic le provides a brief overview of these and other major developments in metal-catalyzed kinetic resolution; strengths and weaknesses of variou s methods are discussed, and different protocols that afford identical or similar optically pure or enriched compounds are compared. Where p ossible, the available mechanistic paradigms that affords a rationale as to the observed stereochemical outcomes are provided.