196212-73-4Relevant academic research and scientific papers
Asymmetric epoxidation of allylic alcohols catalyzed by vanadium-binaphthylbishydroxamic acid complex
Noji, Masahiro,Kobayashi, Toshihiro,Uechi, Yuria,Kikuchi, Asami,Kondo, Hisako,Sugiyama, Shigeo,Ishii, Keitaro
, p. 3203 - 3210 (2015)
A vanadium-binaphthylbishydroxamic acid (BBHA) complex-catalyzed asymmetric epoxidation of allylic alcohols is described. The optically active binaphthyl-based ligands BBHA 2a and 2b were synthesized from (S)-1,1'-binaphthyl-2,2'dicarboxylic acid and N-substituted-O-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 2a were easily performed in toluene with a TBHP water solution to afford (2R)-epoxy alcohols in good to excellent enantioselectivities.
Electrophilic amination of catecholboronate esters formed in the asymmetric hydroboration of vinylarenes
Knight, Frances I.,Brown, John M.,Lazzari, Dario,Ricci, Alfredo,Blacker, A. John
, p. 11411 - 11424 (2007/10/03)
(S)-(4-Methoxyphenyl)-ethyl-1,3,2-benzodioxaborole, (S)-1-(4-chlorophenyl)ethyl-1,3,2-benzodioxaborole and (S)-1-indanyl-1,3,2-benzodioxaborole, intermediates in the catalytic asymmetric hydroboration of 4-chloro- and 4-methoxystyrene, were isolated as pure oils in 75%, 84% and 49% yield respectively. For the first example, amination with N-chloromagnesio-N-methyl-O-trimethylsilylhydroxylamine gave a mixture of (S)-1-(4-methoxyphenyl)-N- methylethylamine in 33% yield, 88% e.e. and (S)-1-(4-methoxyphenyl) ethanol in 31% yield, 86% e.e.. Related results were obtained in the other cases, and the steps of catalytic hydroboration and amination could be combined in a single sequence without isolation of the intermediate Numerous variants were carried out in the amination procedure with only marginal improvements in chemoselectivity. An investigation of the mechanism was carried out using low temperature heteronuclear NMR on 13C-1-(S)-1-(4-chlorophenyl)ethyl-1,3,2-benzodioxaborole. The dual pathway is a result of an irreversible and unselective initial step.
