Different bio/Lewis acid-catalyzed stereoselective aldol reactions in various mediums
作者:Tülay Yıldız、Hasniye Yaşa、Belma Hasdemir、Ayşe S. Yusufoğlu
DOI:10.1007/s00706-017-1967-z
日期:2017.8
Brønsted acids were used for asymmetric aldol reactions of aromatic, heteroaromatic, cyclic, and acyclic six ketones and eleven aldehydes. Optimum reaction conditions were determined by changing temperature and enzyme, ketone, aldehyde, solvent, cofactors types, amounts, and ratios. PPL (porcine pancreatic lipase) of animal and AL-AN (amano lipase A from Aspergillus niger) of fungal origins were the
Facile one-pot fabrication of magnetic nanoparticles (MNPs)-supported organocatalysts using phosphonate as an anchor point through direct co-precipitation method
Novel MNP-supported organocatalysts were prepared by one-pot co-precipitation and surface modification using phosphonate as an anchor point, and exhibited excellent performance in aqueous asymmetric aldol reactions.
An Acid/Base-Regulated Recyclable Strategy for Homogeneous Cinchona Alkaloid-Derived Primary Amine Organocatalysts in Aldol, Vinylogous Michael and Double-Michael Cascade Reactions
作者:Jingwei Wan、Zhiwei Zhao、Falu Wang、Xuebing Ma
DOI:10.1002/ejoc.201500566
日期:2015.9
reusability of the organocatalysts epi-CDNH2, DeMe-QNNH2 and H-CDNH2 over three cycles was investigated in detail. It was found that the organocatalysts were highly effective with respect to catalytic performance, including the yields and stereoselectivities. Furthermore, the recovered organocatalysts in the tenth cycle retained similar excellent enantioselectivities to fresh organocatalysts. However, the
A phosphotungstic acid-supported multifunctional organocatalyst containing 9-amino(9-deoxy)epi-cinchonidine and Brønsted acid and its application in asymmetric aldol reaction
作者:Ling Lan、Guangxin Xie、Tao Wu、Dandan Feng、Xuebing Ma
DOI:10.1039/c6ra08909g
日期:——
or p-substituted benzaldehydes bearing electron-withdrawing substituents (–X and –NO2) afforded good yields (71–96%) and excellent stereoselectivities (anti/syn = 94/6–98/2, 87–97% ee). It was found that the arm length (n) and acid capacity had significant effects on the cooperative catalysis of CDNH2 and Brøsted acid in the aldol reaction. After the completion of the aldol reaction, the catalysts could
A highly stereoselective direct aldol condensation of ketones to aromatic aldehydes was realized; the trichlorosilyl enolether generated in situ in the presence of tetrachlorosilane is activated by catalytic amounts of an enantiomerically pure biheteroaromatic phosphine oxide to react with aldehydes, coordinated as well as activated by the chiral cationic hypervalent silicon species. This Lewis acid-mediated Lewis base-catalyzed transformation allowed, starting from two carbonyl compounds, to directly synthesize beta-hydroxy ketones generally with high anti stereoselectivity and up to 93% ee for the anti isomer. (C) 2010 Elsevier Ltd. All rights reserved.