Dendron-anchored organocatalysts: the asymmetric reduction of imines with trichlorosilane, catalysed by an amino acid-derived formamide appended to a dendron
作者:Marek Figlus、Stuart T. Caldwell、Dawid Walas、Gulen Yesilbag、Graeme Cooke、Pavel Kočovský、Andrei V. Malkov、Amitav Sanyal
DOI:10.1039/b916601g
日期:——
Asymmetric reduction of ketimines 1a–f with trichlorosilane can be catalysed by the Lewis-basic N-methylvaline-derived formamide anchored to a soluble dendron (11c) with good enantioselectivity (≤94% ee) and low catalyst loading (typically 5 mol%) at room temperature in toluene. This protocol represents an improvement and simplification of the isolation procedure and recovery of the catalyst.
Soluble Polymer-Supported Organocatalysts: Asymmetric Reduction of Imines with Trichlorosilane Catalyzed by an Amino Acid Derived Formamide Anchored to a Soluble Polymer
作者:Andrei V. Malkov、Marek Figlus、Mark R. Prestly、Gouher Rabani、Graeme Cooke、Pavel Kočovský
DOI:10.1002/chem.200901573
日期:2009.9.28
A novel polymeric platform for catalyst immobilization has been developed, featuring inverted solubility pattern: soluble in a nonpolar and insoluble in a polar medium. Asymmetric reduction of imines with Cl3SiH (see scheme), catalyzed by chiral formamide anchored to this soluble polymer, proceeds under homogeneous conditions to give chiral amines in high yields and enantioselectivities (≤91 % ee)
Catalyst-free synthesis of tetrahydropyrimidines <i>via</i> formal [3+3]-cycloaddition of imines with 1,3,5-hexahydro-1,3,5-triazines
作者:Long Chen、Kai Liu、Jiangtao Sun
DOI:10.1039/c7ra11973a
日期:——
tetrahydropyrimidines from readily available starting materials has been developed. This process features an unprecedented intermolecular formal [3+3]-annulation of imines and 1,3,5-hexahydro-1,3,5-triazines under catalyst-free conditions. Importantly, differing from previous transformations, the 1,3,5-triazines are firstly utilized as formal 1,3-dipoles in cycloadditionreactions.
New organocatalysts for the asymmetric reduction of imines with trichlorosilane
作者:Andrei V. Malkov、Kvetoslava Vranková、Ralph C. Sigerson、Sigitas Stončius、Pavel Kočovský
DOI:10.1016/j.tet.2009.08.048
日期:2009.11
Asymmetric reduction of prochiral ketimines 1a-f with trichlorosilane can be catalyzed by the Lewis-basic formamides (S)-4a,b, derived from N-methyl valine, with <91% enantioselectivity and low catalyst loading (<= 5 mol %) at room temperature in toluene. (C) 2009 Elsevier Ltd. All rights reserved.