Aryl aldimines, oxaziridination

The oxidation of N-alkyl or N-aryl aldimines or ketimines with f-amyl hydroperoxide in the presence of either M0CI5 or Mo(CO)6 leads to oxaziridine formation, equation (137) [184]. In benzene solution the reaction proceeds rapidly and yields are high (80-95%). The catalytic procedure is considerably more convenient than conventional methods of oxaziridine preparation. 

A new method for enantioselective oxaziridination of aryl aldimines uses meta-chloroperbenzoic acid and a cinchona alkaloid derivative. ( ... 

The derivative (72) (TBS = t-butyldimethylsilyl) from a series of synthesized cinchona alkaloid derivatives is used as a catalyst for the asymmetric oxaziridination of aryl aldimines with m-CPBA in toluene to give tra 5 -(R,R)-oxaziridines with up to 95% ee.438... 

For the transformation of imines to oxaziridines, in general peroxy adds (e.g., Ph-C03H) can be used. For the selective oxygenation of aryl aldimines tert-BuOOH and alumina-supported M0O3 (as a recyclable heterogeneous catalyst) are recommended... 

An efficient, high-yield synthesis of A-alkyl and A-aryl oxaziridine by oxidation of aldimines with buffered Oxone (potassium peroxymonosulfate) has been introduced by Hajipour and Pyne (Equation (47)) <92JCR(S)388>. Oxidation of the aldimine is accomplished in aqueous NaHC03/ acetonitrile or acetone affording the oxaziridine within 15-30 minutes in excellent yield (95-98%). The active oxidizing species in acetone and acetonitrile are thought to be dimethyldioxirane and peroxyimidic acid [MeC(OOH)=NH), respectively. 

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