Asymmetric Epoxidation of Allylic Alcohols Catalyzed by Vanadium–Binaphthylbishydroxamic Acid Complex

A vanadium–binaphthylbishydroxamic acid (BBHA) complex-catalyzed asymmetric epoxidation of allylic alcohols is described. The optically active binaphthyl-based ligands BBHA <b>2a</b> and <b>2b</b> were synthesized from (<i>S</i>)-1,1′-binaphthyl-2,2′-dicarboxylic acid and <i>N</i>-substituted-<i>O</i>-trimethylsilyl (TMS)-protected hydroxylamines via a one-pot, three-step procedure. The epoxidations of 2,3,3-trisubstituted allylic alcohols using the vanadium complex of <b>2a</b> were easily performed in toluene with a TBHP water solution to afford (2<i>R</i>)-epoxy alcohols in good to excellent enantioselectivities