title: Anti-selective epoxidation of methyl alpha-methylene-beta-tert-butyldimethylsilyloxycarboxylate esters. Evidence for stereospecific oxygen atom transfer in a nucleophilic epoxidation process.
abstract: Methyl alpha-methylene-beta-tert-butyldimethylsilyloxycarboxylate esters are found to undergo diastereoselective epoxidation in the presence of potassium tert-butoxide-tert-butyl hydroperoxide to form anti products. In an effort to better understand mechanistic details of the transformation and the basis of diastereoselectivities observed, we studied the epoxidation of substrates with alpha-methylene groups containing (trans) deuterium labels and discovered that oxygen-atom transfer proceeds with > or = 95% stereospecificity in all cases examined. These and other experiments suggest that the mechanism of epoxidation is not distinguishable from a concerted process.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Jakub
authors.initials: J
authors.lastname: Svenda
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Myers
mesh_terms: D002384:Catalysis; D004852:Epoxy Compounds / Q000737:chemistry*; D004952:Esters; D015394:Molecular Structure; D017646:Organosilicon Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: D004852:Epoxy Compounds; D004952:Esters; D017646:Organosilicon Compounds