16735-22-1Relevant academic research and scientific papers
Efficient Mukaiyama–Aldol Reaction with Aqueous Formaldehyde on a Hydrophobic Mesoporous Lewis Acid Polymer
Zhang, Fang,Liang, Chao,Wang, Zhen,Li, Hexing
, p. 818 - 824 (2018)
The design of robust water-compatible solid Lewis acid catalysts in the efficient utilization of aqueous formaldehyde is a challenging task. Herein, we describe an ytterbium triflate containing ordered mesoporous polymer (Yb(OTf)2-MP) that acts as a highly active and selective Lewis acid catalyst for the Mukaiyama–aldol reaction with aqueous formaldehyde. The unique capacity of hydrophobic surface and ordered mesoporosity was able to stabilize the hydrophilic and hydrophobic reactants simultaneously and catalyze the reaction selectively by minimizing water interference at active sites. Accordingly, it enabled a broad range of silyl enol ethers to be used to create structurally diverse β-hydroxy carbonyl molecules efficiently. Notably, the process can be scaled up easily to achieve the gram-scale production of the key intermediate of natural product sarkomycin. Additionally, it is stable under aqueous conditions and can be recovered easily and used repeatedly at least six times.
Palladium-Catalyzed Synthesis of α-Methyl Ketones from Allylic Alcohols and Methanol
Biswal, Priyabrata,Samser, Shaikh,Meher, Sushanta Kumar,Chandrasekhar, Vadapalli,Venkatasubbaiah, Krishnan
supporting information, p. 413 - 419 (2021/11/01)
One-pot synthesis of α-methyl ketones starting from 1,3-diaryl propenols or 1-aryl propenols and methanol as a C1 source is demonstrated. This one-pot isomerization-methylation is catalyzed by commercially available Pd(OAc)2 with H2O as the only by-product. Mechanistic studies and deuterium labelling experiments indicate the involvement of isomerization of allyl alcohol followed by methylation through a hydrogen-borrowing pathway in these isomerization-methylation reactions.
Synthesis of a Bolm's 2,2′-Bipyridine Ligand Analogue and Its Applications
Bedná?ová, Eva,Dra?ínsky, Martin,Malatinec, ?tefan,Císa?ová, Ivana,Lamaty, Frédéric,Kotora, Martin
supporting information, p. 2869 - 2878 (2018/08/17)
A new method of synthesis of an analogue of Bolm's 2,2′-bipyridine ligand based on the catalytic [2+2+2] cyclotrimerization of 1-halodiynes with nitriles was developed. Crucial step of the whole synthesis turned out to be homodimerization of a substituted 2-bromopyridine to the corresponding bipyridine, that was studied and optimized. The newly prepared bipyridine (S,S)-2 was then tested as a chiral ligand in metal-catalyzed enantioselective reactions. Out of the studied reactions the most promising results were obtained in epoxide ring opening (82% yield, 98% ee) and Mukaiyama aldol reaction (>96% yield, 99/1 dr, 92% ee). In the case of Mukaiyama-aldol reaction as well as in the Michael addition, novel ligand 2 proved its robustness compared to Bolm's ligand as it was less sensitive to the purity of used reagents. (Figure presented.).
Visible-Light-Mediated Rose Bengal-Catalyzed α-Hydroxymethylation of Ketones with Methanol
Yang, Jingya,Xie, Dongtai,Zhou, Hongyan,Chen, Shuwen,Duan, Jiaokui,Huo, Congde,Li, Zheng
supporting information, p. 3471 - 3476 (2018/09/12)
A visible-light-mediated α-hydroxymethylation of ketones using methanol as the hydroxymethylating reagent has been developed. Using 1 mol% rose bengal as the photosensitizer and air as the green oxidant, the reactions proceeded smoothly at room temperature. Experimental studies indicate the reaction proceeded via a radical pathway. (Figure presented.).
Dual Lewis Acid/Photoredox-Catalyzed Addition of Ketyl Radicals to Vinylogous Carbonates in the Synthesis of 2,6-Dioxabicyclo[3.3.0]octan-3-ones
Foy, Nicholas J.,Forbes, Katherine C.,Crooke, Anne Marie,Gruber, Maxwell D.,Cannon, Jeffrey S.
, p. 5727 - 5731 (2018/09/21)
A combined Lewis acid/photoredox catalyst system enabled the intramolecular umpolung addition of ketyl radicals to vinylogous carbonates in the synthesis of 2,6-dioxabicyclo[3.3.0]octan-3-ones. This reaction proceeded on a variety of aromatic ketones to provide THF rings in good yield (up to 95%). Although diastereoselectivity was found to be modest (1.4-5:1) for the C-C bond forming reaction, the minor diastereomers were converted to 2,6-dioxabicyclo[3.3.0]octan-3-ones by an efficient Lewis acid-mediated epimerization cascade in up to 90% yield.
Toward chemistry-based design of the simplest metalloenzyme-like catalyst that works efficiently in water
Kitanosono, Taku,Kobayashi, Shu
supporting information, p. 133 - 138 (2015/02/19)
Enzymes exhibit overwhelmingly superior catalysis compared with artificial catalysts. Current strategies to rival enzymatic catalysis require unmodified or minimally modified structures of active sites, gigantic molecular weight, and sometimes the use of harsh conditions such as extremely low temperatures in organic solvents. Herein, we describe a design of small molecules that act as the simplest metalloenzyme-like catalysts that can function in water, without mimicking enzyme structures. These artificial catalysts efficiently promoted enantioselective directtype aldol reactions using aqueous formaldehyde. The reactions followed Michaelis-Menten kinetics, and heat-resistant asymmetric environments were constructed in water.
Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene O-H Insertion Reaction
Nicolle, Simon M.,Lewis, William,Hayes, Christopher J.,Moody, Christopher J.
supporting information, p. 8485 - 8489 (2015/11/27)
Copper- or rhodium-catalyzed reactions of diazocarbonyl compounds with β-hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single-step process starts as a carbene O-H insertion reaction, but is diverted by an intramolecular aldol reaction. Gone astray: Copper- or rhodium-catalyzed reactions of diazocarbonyl compounds with β-hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. The single-step reaction proceeds under mild conditions, starting as a carbene O-H insertion reaction, but then diverting to an intramolecular aldol reaction.
Highly active, water-compatible and easily separable magnetic mesoporous Lewis acid catalyst for the Mukaiyama-Aldol reaction in water
Zhang, Fang,Wu, Xiaotao,Liang, Chao,Li, Xiaoyan,Wang, Zhen,Li, Hexing
, p. 3768 - 3777 (2014/08/05)
A novel magnetic mesoporous Lewis acid catalyst was prepared through immobilizing Yb(OTf)3 on a sodium propylsulphonate and phenyl group co-functionalized magnetic core-mesoporous silica shell composite. The obtained Yb(OTf)2-SO3Na&Ph-MCMSS catalyst had a typical core-shell structure with a Fe3O4 magnetic core, a middle amorphous silica layer and a multifunctional mesoporous silica shell with radial pore channels. In water medium Mukaiyama-Aldol reactions, it exhibited a higher catalytic reactivity than that of the homogeneous catalyst Yb(OTf)3, and control catalysts Yb(OTf)2-SO3Na-MCMSS without phenyl groups inside the mesoporous channels, Yb(OTf)2-SO 3Na&Ph-MCSS without a mesoporous structure, mesoporous Yb(OTf)2-SO3Na&Ph-MCM-41 with an irregular morphology and nonporous Yb(OTf)2-SO3Na-Amberlyst-15 ion-exchange resin. The systematic analysis demonstrated that this excellent catalytic performance could be attributed to the synergetic effect resulting from its radial mesoporous channels and the pore surface hydrophobicity, leading to the increased accessibility of actives sites and the decreased diffusion limitation of reactants. More importantly, this catalyst was stable in water and could be easily separated with a simple magnet and reused at least six times without loss of catalytic activity. This journal is the Partner Organisations 2014.
Iron- and bismuth-catalyzed asymmetric mukaiyama aldol reactions in aqueous media
Kitanosono, Taku,Ollevier, Thierry,Kobayashi, Shu
supporting information, p. 3051 - 3062 (2014/01/06)
We have developed asymmetric Mukaiyama aldol reactions of silicon enolates with aldehydes catalyzed by chiral FeII and BiIII complexes. Although previous reactions often required relatively harsh conditions, such as strictly anhydrous conditions, very low temperatures (-78 °C), etc., the reactions reported herein proceeded in the presence of water at 0 °C. To find appropriate chiral water-compatible Lewis acids for the Mukaiyama aldol reaction, many Lewis acids were screened in combination with chiral bipyridine L1, which had previously been found to be a suitable chiral ligand in aqueous media. Three types of chiral catalysts that consisted of a FeII or BiIII metal salt, a chiral ligand (L1), and an additive have been discovered and a wide variety of substrates (silicon enolates and aldehydes) reacted to afford the desired aldol products in high yields with high diastereo- and enantioselectivities through an appropriate selection of one of the three catalytic systems. Mechanistic studies elucidated the coordination environments around the FeII and BiIII centers and the effect of additives on the chiral catalysis. Notably, both Bronsted acids and bases worked as efficient additives in the Fe II-catalyzed reactions. The assumed catalytic cycle and transition states indicated important roles of water in these efficient asymmetric Mukaiyama aldol reactions in aqueous media with the broadly applicable and versatile catalytic systems. Copyright
An extremely stable and highly active periodic mesoporous Lewis acid catalyst in water-medium Mukaiyama-aldol reaction
Zhang, Fang,Liang, Chao,Chen, Mingzheng,Guo, Haibing,Jiang, Huangyong,Li, Hexing
supporting information, p. 2865 - 2871 (2013/10/08)
A periodic mesoporous Lewis acid catalyst ((OTf)2Sc-SO 3-Ph-PMO) was synthesized through chelating scandium triflate (Sc(OTf)3) with sodium benzenesulfonate-functionalized periodic mesoporous silica (PhSO3Na-Ph-PMO). Compared with homogeneous catalyst Sc(OTf)3 and mesoporous SBA-15-supported scandium triflate catalyst ((OTf)2Sc-SO3-Ph-SBA-15), it exhibited superior catalytic activity and selectivity in water-medium Mukaiyama-aldol reaction. Hydrophobicity tests and substrate adsorption experiments demonstrated that its unique catalytic performance was related to the combined advantage of mesoporosity and hydrophobic microenvironment, which effectively stabilized and concentrated the substances as well as decreased intrinsic mass transfer resistance. Noted that the periodically arranged Lewis acids in the mesoporous silica framework inhibited the active sites leaching, leading to its high catalytic recyclability with almost unchanged catalytic efficiency for more than 10 times in water media.
