Bifunctional Catalysis of the Dedeuteration of Methoxyacetone-1,1,3,3,3-d5

Article abstract of DOI:10.1021/jo00186a021

The dedeuteration of methoxyacetone-1,1,3,3,3-d5 is subject to bifunctional catalysis by 3-(dimethylamino)-propylamine (3DP) and (1R,2S,3R,4R)-3-((dimethylamino)methyl)-1,7,7-trimethyl-2-norbornamine (DTN).These catalysts act by using their primary amino groups to transform the ketone to an iminium ion and their tertiary amino groups to transfer a deuteron internally, changing the iminium ion to an enamine.Although analogous monofunctional bases favor exchange at the methyl position relative to exchange at the methylene position by factors up to 4-fold, bifunctional catalysis by the diamines used favors the methyl group by 11- to 15-fold.Exchange at the methylene group in the presence of DTN was strongly stereoselective.The pro-S deuteron was removed 12-20 times as rapidly as the pro-R deuteron.This is the result of the steric effect of the methoxy substituent.