10383-90-1Relevant articles and documents
Insights into the asymmetric heterogeneous catalysis in porous organic polymers: Constructing A TADDOL-Embedded chiral catalyst for studying the structure-activity relationship[ ]
An, Wan-Kai,Han, Man-Yi,Wang, Chang-An,Yu, Si-Min,Zhang, Yuan,Bai, Shi,Wang, Wei
, p. 11019 - 11028,10 (2014)
Construction of porous organic polymers (POPs) as asymmetric catalysts remains as an important but challenging task. Herein, we exploit the "bottom-up" strategy to facilely synthesize an α,α, α,α-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL)-based chiral porous polymer (TADDOL-CPP) for highly efficient asymmetric catalysis. Constructed through the covalent linkages among the three-dimensional rigid monomers, TADDOL-CPP possesses hierarchical porous structure, high Brunauer-Emmett-Teller (BET) surface area, together with abundant and uniformly-distributed chiral sites. In the presence of [Ti(OiPr)4], TADDOL-CPP acts as a highly efficient and recyclable catalyst in the asymmetric addition of diethylzinc (Et2Zn) to aromatic aldehydes. Based on the direct observation of the key intermediates, the reaction mechanism has been revealed by solid-state 13C magic-angle spinning (MAS) NMR spectroscopy. In combination with the catalytic testing results, characterization on the working catalyst provides further information for understanding the structure-activity relationship. We suggest that the catalytic activity of TADDOL-CPP is largely affected by the structural rigidity, cooperative catalysis, local chiral environment, and hierarchical porous framework. We expect that the information obtained herein will benefit to the designed synthesis of robust POP catalysts toward practical applications.
On the mechanism of addition of lithium pinacolone enolate to benzaldehyde: Polar or electron transfer?
Yamataka, Hiroshi,Sasaki, Daizo,Kuwatani, Yoshiyuki,Mishima, Masaaki,Tsuno, Yuho
, p. 9975 - 9979 (1997)
The carbonyl-carbon kinetic isotope effect (KIE) and the substituent effect were measured for the reaction of lithium pinacolone enolate (CH2=C(OLi)C(CH3)3) with benzaldehyde, and the results were compared with those for other lithium reagents such as MeLi, PhLi, and CH2=CHCH2Li. Ab initio MO calculations (HF/6-31+G*) were carried out to estimate the equilibrium IE on the addition to benzaldehyde. A carbonyl addition reaction, in general, proceeds by way of either a polar direct nucleophilic attack (PL) in a one-step or a two-step process going through a radical ion intermediate (eq 1). The carbonyl-carbon KIE is of primary nature for the PL or the RC rate-determining ET mechanism, while it is considered to be secondary for the ET rate-determining mechanism. The reaction of lithium pinacolone enolate with benzaldehyde gave a small positive KIE (12k/13k = 1.019), which is larger than the theoretical equilibrium IE (12K/13K = 1.006) determined by the MO calculations. Thus, there is a reaction-coordinate contribution to the observed KIE. This is in sharp contrast to the absence of KIE (12k/14k = 1.000) measured previously for the MeLi addition. Dehalogenation and enone-isomerization probe experiments showed no evidence of a single electron transfer to occur during the course of the reaction. The primary carbonyl-carbon KIE together with the substituent effect and chemical probe experiments led to the conclusion that the reaction of lithium pinacolone enolate with benzaldehyde proceeds via the polar mechanism.
Reaction of magnesium pinacolone enolate with benzaldehyde: Polar or ET mechanism?
Yamataka, Hiroshi,Shimizu, Makoto,Mishima, Masaaki
, p. 127 - 129 (2002)
The carbonyl-carbon kinetic isotope effect (KIE) and the substituent effect were measured for the reaction of magnesium pinacolone enolate (CH2=C(OMgBr)C(CH3)3, 1) with benzaldehyde. The results were compared with those for lithium enolate (CH2=C(OLi)C(CH3)3, 2). A normal carbonyl-carbon KIE, a medium-sized Hammett ρ value and the results of chemical probe experiments indicated that the reaction of 1 proceeds via the polar mechanism as in the reaction of 2.
BIOSYNTHESIS OF THE BENZOYL MOIETY OF COCAINE FROM CINNAMIC ACID VIA (R)-(+)-3-HYDROXY-3-PHENYLPROPANOIC ACID
Bjorklund, Jeffrey A.,Leete, Edward
, p. 3883 - 3888 (1992)
trans-Cinnamic acid and the N-acetylcysteamine thioester of -trans-cinnamic acid served as precursors of the benzoyl moiety of cocaine when fed to intact Erythroxylum coca plants.The specific incorporation of the thioester in
Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
Chen, Suqing,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong,Yu, Dongkun,Zhao, Xinhui
, p. 645 - 656 (2020/05/14)
The reductive carbonylation of aryl iodides to aryl aldehydes possesses broad application prospects. We present an efficient and facile Rh-based catalytic system composed of the commercially available Rh salt RhCl3·3H2O, PPh3 as phosphine ligand, and Et3N as the base, for the synthesis of arylaldehydes via the reductive carbonylation of aryl iodides with CO and H2 under relatively mild conditions with a broad substrate range affording the products in good to excellent yields. Systematic investigations were carried out to study the experimental parameters. We explored the optimal ratio of Rh salt and PPh3 ligand, substrate scope, carbonyl source and hydrogen source, and the reaction mechanism. Particularly, a scaled-up experiment indicated that the catalytic method could find valuable applications in industrial productions. The low gas pressure, cheap ligand and low metal dosage could significantly improve the practicability in both chemical researches and industrial applications.
Catalytic Enantioselective [2,3]-Rearrangements of Allylic Ammonium Ylides: A Mechanistic and Computational Study
West, Thomas H.,Walden, Daniel M.,Taylor, James E.,Brueckner, Alexander C.,Johnston, Ryne C.,Cheong, Paul Ha-Yeon,Lloyd-Jones, Guy C.,Smith, Andrew D.
, p. 4366 - 4375 (2017/04/04)
A mechanistic study of the isothiourea-catalyzed enantioselective [2,3]-rearrangement of allylic ammonium ylides is described. Reaction kinetic analyses using 19F NMR and density functional theory computations have elucidated a reaction profile
Metathesis Reaction of Diazo Compounds and para-Quinone Methides for C-C Double Bond Formation: Synthesis of Tetrasubstituted Alkenes and Quinolinones
Huang, Bo,Shen, Yangyong,Mao, Zhenjun,Liu, Yu,Cui, Sunliang
, p. 4888 - 4891 (2016/10/18)
The para-quinone methides (p-QMs) are activated by Lewis acid and then attacked by diazo compounds. The following rearrangement leads to nitrogen gas extrusion and C-C double bond formation to constitute a metathesis reaction process. Therefore, the diazo
Asymmetric 1,2-Perfluoroalkyl Migration: Easy Access to Enantioenriched α-Hydroxy-α-perfluoroalkyl Esters
Wang, Pan,Feng, Liang-Wen,Wang, Lijia,Li, Jun-Fang,Liao, Saihu,Tang, Yong
, p. 4626 - 4629 (2015/04/27)
This study has led to the development of a novel, highly efficient, 1,2-perfluoro-alkyl/-aryl migration process in reactions of hydrate of 1-perfluoro-alkyl/-aryl-1,2-diketones with alcohols, which are promoted by a Zn(II)/bisoxazoline and form α-perfluoro-alkyl/-aryl-substituted α-hydroxy esters. With (-)-8-phenylmenthol as the alcohol, the corresponding menthol esters are generated in high yields with excellent levels of diastereoselectivity. The mechanistic studies show that the benzilic ester-type rearrangement reaction takes place via an unusual 1,2-migration of electron-deficient trifluoromethyl group rather than the phenyl group. The overall process serves as a novel, efficient, and simple approach for the synthesis of highly enantioenriched, biologically relevant α-hydroxy-α-perfluoroalkyl carboxylic acid derivatives.
Gold-catalyzed 1,3-transposition of ynones
Kazem Shiroodi, Roohollah,Soltani, Mohammad,Gevorgyan, Vladimir
, p. 9882 - 9885 (2014/08/05)
An efficient, regioselective gold-catalyzed 1,3-transposition reaction of ynones and diynones has been developed. It was found that stereoelectronic (interrupted conjugation) and electronic (extended conjugation) factors could efficiently govern the regio
Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines
Davies, Paul W.,Martin, Nicolas,Spencer, Neil
, p. 839 - 846 (2011/08/10)
Isotopic labelling studies were performed to probe a proposed 1,2-aryl shift in the gold-catalysed cycloisomerisation of alkynyl aziridines into 2,4-disubstituted pyrroles. Two isotopomers of the expected skeletal rearrangement product were identified usi