Homogeneous catalysts stereoselectivity mechanism

In all these molecules, the carbon atom where the potential handedness resides is labeled with an asterisk. Asymmetric catalj4ic transformations of most of these prochiral substrates will be discussed later. In particular, we will see the basic mechanisms of hydrogenation of 3.42 and 3.43, asymmetric epoxidation of 3.44, stereoselective polymerization of propylene, and asymmetric dihydroxylation of 3.46. Asymmetric isomerization of 3.47 is one of the critical steps in a homogeneous catalyst-based industrial manufacturing process for L-menthol. 

Although significant advances in stereoselective epoxide polymerization have been achieved over the last half-century, few known catalysts are capable of excellent levels of stereocontrol. Historically, most catalysts for epoxide polymerization have been of the heterogeneous variety and have exhibited poor selectivity. It is our opinion that the most fertile area for future catalyst exploration involves homogeneous, discrete catalysts that are capable of involving multiple metal centers in the polymerization mechanism. If the spatial environment of the active catalyst is precisely controlled, new generations of stereoselective epoxide polymerization catalysts will become available. Our current research focuses on the search for such catalysts. 

---