Monoperoxycamphoric acid, oxidation

A chiral substituent on nitrogen can direct the predominant attack of an oxidizing agent to one dia-stereotopic face of an imine. Ratios as high as 97 3 were observed in a series of imines derived from a-methylbenzylamine (equation 43). The oxidation of achiral imines with optically active peroxy acids, most notably monoperoxycamphoric acid [(+)-MPCA], do afford optically active oxaziridines, but not generally in synthetically useful optical ratios, but ratios as high as 80 20 have been reported. ... 

Under comparatively drastic reaction conditions, camphor is oxidized with ring cleavage to give camphoric acid (69). Alternatively, bomeol may be used as starting material. Both enantiomers are commercially available. As oxidants nitric acid is most frequently used the best results are obtained when ammonium vanadate is added as a catalyst68. The ( + )-enantiomer was used for the preparation of monoperoxycamphoric acid, which is an isomeric mixture and difficult to separate69. The peracid has been applied with limited success as an enantioselective epoxidation reagent (Section D.4.5.2.). 

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