Asymmetric Reduction of Oxime Ethers Promoted by Chiral Spiroborate Esters with an O₃BN Framework

Abstract

Enatioselective reduction of oxime ethers promoted by chiral spiroborate esters with an O3BN framework is reported for the first time. In the presence of (R,S)-1, 11 aralkyloxime ethers are reduced by borane-THF at 0-5 degrees C to give (S)-1-aralkylamine in high yield and excellent enatiomeric excess (up to 98% ee). Influence of reaction conditions on the enantioselectivity of the reduction is investigated, and a possible mechanism of the catalytic reduction is suggested.

A Versatile Ru Catalyst for the Asymmetric Transfer Hydrogenation of Both Aromatic and Aliphatic Sulfinylimines

“…(R)-1-(4-Nitrophenyl)ethanamine (2 n): [52] Computational Details: [Ru(para-cymene)(2-amino-2-methylpropan-1-ol)] was the catalyst, and the N-(tert-butylsulfinyl)ketimine 1 a, derived from acetophenone, was chosen as the substrate for the theoretical calculations. No simplification was made in any of the reactant molecules selected for the computational study.…”

Reactions of Aldehydes and Ketones and their Derivatives

“…An enantioselective metal-free hydrosilylation of aromatic ketones (and also of their imines) employs a quinolyloxazoline (88), which brings about a relatively long-range ee induction. 262 (88) N N O Ph * A rhodium(I)-diphosphine complex which is P -chiral catalyses enantioselective hydrosilylation of a range of simple ketones.…”

“…262 (88) N N O Ph * A rhodium(I)-diphosphine complex which is P -chiral catalyses enantioselective hydrosilylation of a range of simple ketones. 263 After acidic workup, the corresponding ee alcohols are obtained in high yields and ees up to 99%.…”

Industrial Catalysts for Regio‐ or Stereo‐Selective Oxidations and Reductions. A Review of Key Technologies and Targets

“…[47] The use of CBS-type catalysts has been extended to the reduction of oximes into chiral amines. Chu et al [48] have described the BINOL-proline-borate complex shown in Figure 1.39 that can reduce acetophenone oxime into chiral 1-phenylethylamine with 98 % ee, but the ee drops when the borate complex is used catalytically. …”