Esters spiroborate

Chu, Y, Shan, Z., Liu, D. and Sun N. Asymmetric Reduction of Oxime Ethers Promoted by Chiral Spiroborate Esters with an O3BN Framework. J. Org. Chem. 2006, 71, 3998-4001. 

Enantioselective reduction of oxime ethers promoted by chiral spiroborate esters (10) with an O3BN framework is reported. In the presence of (R,S)-10, aralkyloxime ethers are reduced by borane-THF at give (S)-l-aralkylamine in high yield and excellent enatiomeric excess (up to 98% ee). A possible mechanism (Scheme 13) of the catalytic reduction is suggested.310... 

Spiroborate esters derived from a-pinene and various diols catalyse borane reduction of aryl alkyl ketones in high yield and ee. ... 

DFT has been used to investigate the mechanism of enantioselective borane reduction of -acetophenone 0-methyl oxime, using a stable chiral spiroborate ester. ... 

DFT investigation of two reaction pathways in the borane reduction of the ( )-acetophenone O-Me oxime catalysed by spiroborate ester at the B3LYP/6-31G(d,p) level of theory indicates that the reaction is accomplished via four steps. The reactants, products, transition states and intermediates are optimized at the B3LYP/6-31G(d,p) level. The solvent effect considered at the B3LYP/6-31G(d,p) level using the PCM indicates that THF has no great influence on the enantioselectivity of this reduction. ... 

Highly enantioselective reduction of heterocyclic aromatic ketones with borane and the spiroborate ester derived from (S)-diphenyl prolinol... 

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