A significant improvement in enantioselectivity, yield, and reactivity for the copper-bi-o-tolyl bisoxazoline-catalyzed asymmetric allylic oxidation of cyclic olefins using recoverable SBA-15 mesoporous silica material
摘要:
A series of chiral bi-o-tolyl bisoxazoline ligands 1 and 2 were conveniently synthesized on a gram scale from inexpensive and commercially available 3-methyl benzoic acid in eight steps. The catalytic and induced asymmetric effects of the chiral copper (I) complexes of these ligands on the asymmetric allylic oxidation of cycloolefins were investigated in the presence of various nano-sized additives. When SBA-15 mesoporous silica was used in conjunction with these ligands very highly enantioselectivities (up to 97% ee) and excellent yields (up to 99%) of the corresponding chiral allylic esters were obtained in a reasonably short period of time. (C) 2013 Elsevier Ltd. All rights reserved.
Heterogenization of chiral mono oxazoline ligands by grafting onto mesoporous silica MCM-41 and their application in copper-catalyzed asymmetric allylic oxidation of cyclic olefins
spectroscopy (EDX), CHN analysis, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The catalytic and induced asymmetric effects of the chiralcopper (I) complexes of these new chiral supported heterogeneous catalysts on the asymmetricallylicoxidation of cycloolefins were investigated under different conditions. Reactions using the catalyst exhibited moderate to good
development of biologically active compounds. Moreover, the chiral diamino alcohols, 1, can be used in the asymmetrical reactions as a catalyst to increase reaction rate and as a chiral auxiliary or chiralligand to induce the chirality in the synthesis of chiral products. Enantioselective allylicoxidation of olefins using copperchiral complexes have been the subject of great interest during the
Studies on enantioselective allylic oxidation of olefins using peresters catalyzed by Cu(i)-complexes of chiral pybox ligands
作者:Sandeep K. Ginotra、Vinod K. Singh
DOI:10.1039/b612423b
日期:——
Enantioselective allylic oxidation of olefins with various peresters, using a catalytic amount of Cu(I)-pybox complex, can be tuned to achieve high asymmetric induction (up to 98% ee) by choosing a unique combination of a ligand and a perester at room temperature. The asymmetric induction in the reaction strongly depends on the nature of the substituents attached to the aryl ring of peresters. The
characterization of the complex confirmed the involvement of both dentate parts of the ligands, the oxygen and nitrogen atoms, in complexation with copper. The utilization of this amido-oxazoline ligands in the copper-catalyzed enantioselective esterification of allylic CH bonds of cyclic olefins with tert-butyl-4-nitrobenzoperoxoate resulted in the highest activities, yields (up to 95%) and enantioselectivities
Highly Enantioselective Copper−Bisoxazoline-Catalyzed Allylic Oxidation of Cyclic Olefins with <i>tert</i>-Butyl <i>p</i>-nitroperbenzoate
作者:Merritt B. Andrus、Ziniu Zhou
DOI:10.1021/ja026266i
日期:2002.7.1
Catalytic asymmetric allylicoxidation of cyclicolefins ocurrs for the first time in very high (94-99% ee) enantioselectivity using copper(I) complexes of malonyl derived bisoxazolines and tert-butyl p-nitroperbenzoate giving allyl benzoates in moderate yield. The copper complex, 15 mol %, was used in acetonitrile at -20 degrees C over an extended period, 5-12 d, with excess olefin together with one