59452-90-3Relevant academic research and scientific papers
Synthesis of rac-ɑ-aryl propionaldehydes via branched-selective hydroformylation of terminal arylalkenes using water-soluble Rh-PNP catalyst
Chen, Fen-Er,Gao, Peng,Ke, Miaolin,Liang, Guanfeng,Ru, Tong
, (2021/08/26)
This work detailed the preparation of a class of water-soluble PNP ligands that differed by the nature of the substitute on phenyl ring of ligands. These ligands were incorporated into water-soluble rhodium-PNP complex catalysts that were used to regioselective hydroformylation of a series of terminal arylalkenes, providing efficient access to rac-α-aryl propionaldehydes in good to excellent yield (up to 97%) and branched-regioselectivity (up to 40:1 b/l ratio). Furthermore, gram-scale and diverse synthetic transformation demonstrated synthetic application of this methodology for non-steroidal antiinflammatory drugs.
Copper-catalyzed vinylogous aerobic oxidation of unsaturated compounds with air
Zhang, Hai-Jun,Schuppe, Alexander W.,Pan, Shi-Tao,Chen, Jin-Xiang,Wang, Bo-Ran,Newhouse, Timothy R.,Yin, Liang
, p. 5300 - 5310 (2018/04/24)
A mild and operationally simple copper-catalyzed vinylogous aerobic oxidation of β,γ- and α,β-unsaturated esters is described. This method features good yields, broad substrate scope, excellent chemo- and regioselectivity, and good functional group tolerance. This method is additionally capable of oxidizing β,γ- and α,β-unsaturated aldehydes, ketones, amides, nitriles, and sulfones. Furthermore, the present catalytic system is suitable for bisvinylogous and trisvinylogous oxidation. Tetramethylguanidine (TMG) was found to be crucial in its role as a base, but we also speculate that it serves as a ligand to copper(II) triflate to produce the active copper(II) catalyst. Mechanistic experiments conducted suggest a plausible reaction pathway via an allylcopper(II) species. Finally, the breadth of scope and power of this methodology are demonstrated through its application to complex natural product substrates.
Pummerer Cyclization Revisited: Unraveling of Acyl Oxonium Ion and Vinyl Sulfide Pathways
Li, Xin,Carter, Rich G.
, p. 5541 - 5545 (2018/09/25)
Two viable pathways (vinyl sulfide and acyl oxonium ion) for the Pummerer cyclization have been unraveled that expand the reaction scope and capabilities. Use of Br?nsted-enhanced Lewis acidity was key to realization of the vinyl sulfide pathway, whereas selective complexation of the sulfur lone pair facilitated the unprecedented acyl oxonium ion pathway. Preliminary mechanistic investigations support these hypotheses. A range of substrates have been explored to understand the reaction parameters.
Dual Catalysis Using Boronic Acid and Chiral Amine: Acyclic Quaternary Carbons via Enantioselective Alkylation of Branched Aldehydes with Allylic Alcohols
Mo, Xiaobin,Hall, Dennis G.
, p. 10762 - 10765 (2016/09/09)
A ferrocenium boronic acid salt activates allylic alcohols to generate transient carbocations that react with in situ-generated chiral enamines from branched aldehydes. The optimized conditions afford the desired acyclic products embedding a methyl-aryl quaternary carbon center with up to 90% yield and 97:3 enantiomeric ratio, with only water as the byproduct. This noble-metal-free method complements alternative methods that are incompatible with carbon-halogen bonds and other sensitive functional groups.
An air-stable cationic iridium hydride as a highly active and general catalyst for the isomerization of terminal epoxides
Humbert, Nicolas,Vyas, Devendra J.,Besnard, Céline,Mazet, Clément
supporting information, p. 10592 - 10595 (2014/10/15)
We describe the use of an air-stable iridium hydride catalyst for the isomerization of terminal epoxides into aldehydes with perfect regioselectivity. The system operates at low loadings of catalyst (0.5 mol%), is highly practical, scalable, and tolerates functional groups that would not be compatible with Lewis acids typically used in stoichiometric amounts. Evidence for a rare hydride mechanism are provided. This journal is the Partner Organisations 2014.
Isomerization of terminal epoxides by a [Pd-H] catalyst: A combined experimental and theoretical mechanistic study
Vyas, Devendra J.,Larionov, Evgeny,Besnard, Celine,Guenee, Laure,Mazet, Clement
supporting information, p. 6177 - 6183 (2013/06/04)
An unusual palladium hydride complex has been shown to be a competent catalyst in the isomerization of a variety of terminal and internal epoxides. The reaction displayed broad scope and synthetic utility. Experimental and theoretical evidence are provided for an unprecedented hydride mechanism characterized by two distinct enantio-determining steps. These results hold promise for the development of an enantioselective variant of the reaction.
Complementary catalytic strategies to access α-chiral aldehydes
Mazet, Clement
, p. 658 - 662 (2013/11/06)
The present article summarizes the development of two novel and complementary catalytic methods to access α-chiral aldehydes. A C1-symmetric chiral (P,N) ligand with a structure derived from the ubiquitous binepine scaffold has been specifically designed for the Pd-catalyzed α arylation of aldehydes to access indane derivatives with a well-defined quaternary stereocenter in high yields and excellent enantioselectivities. In addition, a dinuclear palladium hydride catalyst has been synthesized for the isomerization of terminal and trisubstituted epoxides into aldehydes and ketones respectively. Combined experimental and theoretical investigations pointed to an unprecedented 'epoxide-opening/hydride-transfer' sequence. The mechanism also features two distinct enantio-determining steps in the kinetic resolution of racemic epoxides. Schweizerische Chemische Gesellschaft.
β-tert-Butyl aspartate as an organocatalyst for the asymmetric α-amination of α,α-disubstituted aldehydes
Theodorou, Alexis,Papadopoulos, Giorgos N.,Kokotos, Christoforos G.
supporting information, p. 5438 - 5443 (2013/07/05)
The enantioselective α-amination reaction of α,α- disubstituted aldehydes can lead to a variety of enantioenriched amino aldehydes, amino alcohols, and amino acids. After screening a variety of amino acids and their derivatives, we identified a cheap, simple, commercially available aspartic acid derivative that can catalyze efficiently the reaction between α,α-disubstituted aldehydes and dialkyl azodicarboxylates. The reaction proceeds smoothly leading to the corresponding α-aminated adducts in moderate to quantitative yields and moderate to high enantioselectivities (up to 96% ee). Finally, the conversion of these adducts to α,α-disubstituted quaternary amino acids is also described.
Highly selective hydroformylation of vinylarenes to branched aldehydes by [Rh(cod)Cl]2 entrapped in ionic liquid modified silica sol-gel
Hamza, Khalil,Blum, Jochanan
, p. 4706 - 4710 (2008/03/13)
A co-entrapped mixture of [Rh(cod)Cl]2 and Na[Ph 2P-3-(C6H4SO3)] within a silica sol-gel matrix modified with ca. 5% of 1-butyl-3-[3-(trimethoxysilyl)propyl] imidazolium chloride catalyzes, in n-heptane, the hydroformylation of a variety of vinylarenes. At 50°C and under 6.9 bar each of H2 and CO the reaction is high-yielding and highly selective. Non-hindered substrates give >95 % of branched aldehydes and only 5% of the linear isomers. The ceramic catalyst is leach-proof and recyclable. It does not lose its high catalytic activity and selectivity for at least four runs. The selectivity depends on the pressure of the gases, the temperature and the solvent. The electronic nature has no influence on the selectivity, but the latter is diminished by steric effects. Upon omission of the sol-gel component, the catalyst deteriorates and practically loses its activity after the first half-life of the reaction. In the absence of the ionic liquid, the catalyst undergoes substantial leaching. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
A Simple and Efficient Conversion of Aldehyde Acetals into Esters
Sugai, Saburo,Kodama, Takashi,Akaboshi, Sanya,Ikegami, Shiro
, p. 99 - 105 (2007/10/02)
The reaction of aldehydic acetals with hypochlorous acid in acetic acid-acetone afforded the corresponding esters in excellent yields.From cyclic acetals, only the corresponding hydroxyalkyl esters were obtained.Keywords - acetal; hypochlorite; hypochlorous acid; conversion; ester; hydroxyalkyl ester; regioselectivity
