[77402-46-1] · C26H20MoN2O7 · Oxoperoxobis(N-phenylbenzohydroxamato)molybdenum(VI) · (MW 568.42)
Physical Data: mp 150 °C (dec).
Solubility: sol dichloromethane, 1,2-dichloroethane; insol water, hexane.
Form Supplied in: orange-yellow crystals.
Preparative Methods: by stirring a mixture of MoO2(acac)2 (1 mmol) and hydroxamic acid (PhCON(Ph)OH) (2 mmol) at 25 °C for 3 h, followed by treating the white solid of MoO2(PhCON(Ph)O)2, so formed, with excess of 30% H2O2 at 25 °C.
Primary alcohols are oxidized to aldehydes and secondary alcohols to ketones. Yields are fair to good. The mixture of the Mo complex and the alcohol in 1,2-dichloroethane is refluxed for 4 h. The product is isolated after the usual workup. Cyclododecanol and 2-octanol have been oxidized in >95% yield to their corresponding ketones, whereas aldehydes are obtained from benzyl alcohol and dodecanol in 80 and 63% yield, respectively.
The reagent is quite reluctant to react with simple alkenes, although molybdenum diperoxo compounds such as Mimoun's reagent are known to epoxidize alkenes.2 However, allylic alcohols were converted easily to a,b-epoxy alcohols in fair yields (60-70% isolated). It is worth noting that more stereoselectivity is obtained in this reaction using a stoichiometric amount of the monoperoxo complex than that observed with t-Butyl Hydroperoxide in combination with Hexacarbonylmolybdenum.3 This is illustrated in Table 1.
Sandoz Research Institute, East Hanover, NJ, USA