Enantioselective Reduction of Imines Catalyzed by a Rhenium(V)−Oxo Complex
摘要:
An air- and moisture-tolerant enantioselective hydrosilylation of N-phosphinyl imines employing a chiral Re(V)-oxo complex as a catalyst is described. The chiral catalyst is a cyanobis(oxazoline) (CNbox)-ligated rhenium-oxo complex of the general formula (CNbox)Re(O)Cl2(OPPh3). Using this catalyst, a wide range of aromatic imines (including cyclic, acyclic, and heteroaromatic), alpha-iminoesters, and alpha,beta-unsaturated imines are reduced with good to excellent enantioselectivities.
Synthesis of Air- and Moisture-Stable, Storable Chiral Oxorhenium Complexes and Their Application as Catalysts for the Enantioselective Imine Reduction
salicyloxazoline based oxorhenium(V) complexes have been synthesized and their catalytic application for the asymmetricreduction of ketimines using hydrosilane as hydride source is disclosed. A broad substrate scope, high yields, and excellent enantioselectivities (up to 99 %) are attained. Furthermore, the syntheses of enantiopure α‐amino esters, γ‐ and δ‐lactams, and isoindolinones have also been carried
合成了空气/水分稳定,晶体和可储存的手性水杨基恶唑啉基氧化(V)配合物,并公开了其在氢化硅烷作为氢化物源的情况下催化不对称还原酮亚胺的催化应用。获得了广泛的底物范围,高收率和出色的对映选择性(最高99%)。此外,对映体纯α-氨基酯,γ-和δ-内酰胺以及异吲哚啉酮的合成也已使用该方法进行。最后,该方法已应用于具有药物相关性的合成靶标,例如R -(+)-沙丁胺碱和R -(+)-crispine A.
Enantioselective MSPV Reduction of Ketimines Using 2-Propanol and (BINOL)Al<sup>III</sup>
作者:Christopher R. Graves、Karl A. Scheidt、SonBinh T. Nguyen
DOI:10.1021/ol060110w
日期:2006.3.1
A highly enantioselective Meerwein-Schmidt-Ponndorf-Verley (MSPV) reduction of N-phosphinoyl ketimines by (BINOL)Al-III/2-propanol is reported. Yields ranging between 79 and 85% with high enantiomeric excesses (93-98%) are observed for a wide range of structurally diverse ketimines. A [2.0.4] bicyclic chelation model is proposed to account for this high selectivity.