NEW METHODS FOR STEREOSELECTIVE ADDITIONS TO CARBONYLS

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DESCRIPTION: The principal investigator notes that he is engaged in a research program, the aims of which are to discover new stereoselective and chemoselective reactions and reagents in organic synthesis. He states that he uses the tools of mechanistic organic chemistry to uncover the origin of asymmetric induction in reactions that proceed with high levels of selectivity, then uses these results as a guide in the investigation of new reactions that exhibit similar levels of stereoselectivity. The principal investigator indicates that he is continuing to study the mechanism of Lewis acid mediated nucleophilic additions to acetals and that he has developed a method which allows him to determine the level of stereospecificity in these reactions and thereby distinguish between an SN1 and an SN2 mechanism. It is noted that in this proposal, a related method is described that is being applied to chiral acyclic acetals. These substrates were said to have been chosen because they display an unusual stereochemical dependence on the nature of the alkyl group of the acetal. These mechanistic studies are noted to have led the principal investigator to explore new methods for achieving remote asymmetric induction in the Diels-Alder reaction via chiral vinyl oxocarbenium ions. He indicates that he is extending this to intramolecular Diels-Alder reactions and that this method is also being applied to the synthesis of the HMG-CoA reductase inhibitor dihydrocompactin.