Oxaziridines catalyze C–H oxidation selectively

The oxaziridines shown catalyze the regioselective hy-droxylation of unactivated C–H bonds, according to a new study (J. Am. Chem. Soc. 2005, 127, 15391). Alkane hydroxylation remains a formidable challenge in reaction design, write Justin Du Bois and Benjamin H. Brodsky of Stanford University. Certain oxaziridines are known to convert alkanes to alcohols stoichiometrically. Brodsky and Du Bois now report novel N-alkoxysulfonyl oxaziridines that can be used to perform such hydroxylations catalytically. The oxaziridines were generated in situ by treating the corresponding imine precursors with hydrogen peroxide and a suitable cocatalyst. (The oxygen atom from H₂O₂ is shown in red.) The researchers find that the oxaziridine system performs regioselective and stereospecific oxidations of a variety of aliphatic substrates, including alkenes and alcohols. Guided by computational modeling, they are now refining the catalyst to improve turnover rate and substrate scope.