Pyrimidine-Derived Prolinamides as Recoverable Bifunctional Organocatalysts for Enantioselective Inter- and Intramolecular Aldol Reactions under Solvent-Free Conditions
作者:Pascuala Vizcaíno-Milla、José M. Sansano、Carmen Nájera、Béla Fiser、Enrique Gómez-Bengoa
DOI:10.1002/ejoc.201500007
日期:2015.4
ChiralL-prolinamides 2 containing the (R,R)- and (S,S)-trans-cyclohexane-1,2-diamine scaffold and a 2-pyrimidinyl unit are synthesized and used as general organocatalysts for intermolecular and intramolecular aldolreactions with 1,6-hexanedioic acid as a co-catalyst under solvent-free conditions. The intermolecular reaction between ketone–aldehyde and aldehyde–aldehyde must be performed under wet
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.
recognized for its obvious advantages cheap and readily available. A new type of prolinamide organocatalysts, derived from carbohydrate, was synthesized in high yield, and the novel organocatalysts were applied to the direct asymmetric aldolreactions of cyclohexanone and various aromatic aldehydes. The corresponding aldol products were obtained in high yields (up to 99%) with excellent diastereoselectivities
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