ORGN 396 |
| Over the past 30 years enantioselective catalysis has become one of the most important frontiers in exploratory organic synthetic research. During this time, remarkable advances have been made in the development of organometallic asymmetric catalysts that in turn have provided a wealth of enantioselective oxidation, reduction, pi-bond activation and Lewis acid catalyzed processes. Surprisingly, however, relatively few asymmetric transformations have been reported which employ organic molecules as reaction catalysts, despite the accordant potential for academic, economic and environmental benefit. With this in mind, we recently embarked upon the development of a new strategy for enantioselective organocatalysis that would be amenable to a diverse range of asymmetric transformations. We hypothesized that the reversible formation of iminium ions from a,b-unsaturated aldehydes and amines (eq 2) might emulate the equilibrium dynamics and pi-orbital electronics that are inherent to Lewis acid catalysis (eq 1), thereby providing a new platform for the design of organocatalytic processes. In this presentation, we will demonstrate that this new catalysis concept has successfully been applied to a large variety chemical transformations including the first highly enantioselective organocatalytic Diels-Alder, Nitrone cycloaddition, Friedel–Crafts alkylation and conjugate addition reactions. We will further outline a new enamine catalysis sequence that combines Lewis acid and organocatalysis to rapidly construct carbohydrate architecture in a modular and stereodefined fashion. Application of this new technology to the rapid production of fully differentially protected sugar and amino-sugar moities will be highlighted.
|
|
Elias J. Corey Award for Outstanding Original Contribution in Organic Synthesis by a Young Investigator
1:20 PM-5:00 PM, Tuesday, 15 March 2005 Convention Center -- Ballroom 20A-B, Oral
Division of Organic Chemistry |
