A subtle change in catalyst structure can sometimes improve catalytic activity dramatically, as we found in our recent study on α-aminoxylation, tandem O-nitroso aldol/Michael reactions, and Mannich reactions catalyzed by the siloxyproline 4, a highly active proline surrogate (Scheme 1).[1] The simple introduction of a siloxy group into the proline structure leads to an increase in the catalytic activity, thus allowing a decrease in catalyst loading ...
