Intermediates of asymmetric oxidation processes catalyzed by vanadium(V) complexes

The [VO(acac)(2)]/Schiff base [R-2-(N-3,5-di-tert-butylsalicylidene)amino-2-phenyl-1-ethanol, S-2-(N-3,5-di-tert-butylsalicylidene)amino-3,3-dimethyl-1-butanol, S-2-(N-3,5-di-tert-butylsalicylidene)amino-3-methyl-1-butanol, or R-2-(N-3,5-di-tert-butylsalicylidene)amino-3-phenyl-1-propanol]/H2O2 catalytic systems for the asymmetric oxidation of sulfides and the [VO(acac)(2)]/(3bR,4aR)-2-(3,4,4-trimethyl-3b,4,4a,5-tetrahydrocyclopropa[3,4]cyclopenta[ 1,2-c]pyrazol-1-yl)ethanol/tert-butyl hydroperoxide/TBHP and VO(OAlkyl)(3)/[2,2]paracyclophane-4-carboxylic acid N-(l, I -dimethylethyl)-N-hydroxamide/TBHP catalytic systems for the asymmetric epoxidation of allylic alcohols were studied using C-13, V-51, and O-17 NMR spectroscopy. The key intermediates of these systems (peroxo and alkylperoxo complexes of vanadium(V)) were detected, their structures in solution were studied, and the reactivity was evaluated.