2901-41-9Relevant articles and documents
Ni-Catalyzed C(sp3)–O Arylation of α-Hydroxy Esters
Monteith, John J.,Rousseaux, Sophie A. L.
, p. 9485 - 9489 (2021/12/09)
A Negishi cross-coupling of α-hydroxy ester derivatives and arylzinc reagents has been developed. This reaction tolerates both primary and secondary C(sp3)–O alcohol precursors and achieves efficient cross-coupling under Ni catalysis without the need for added external metal reductant, photocatalyst, or additives. The arylation of readily accessible C(sp3)–O electrophiles in this operationally simple, rapid, and mild reaction provides a complementary way of accessing desirable α-aryl ester products.
Method for preparing organic carboxylic ester through combined catalysis of aryl bidentate phosphine ligand
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Paragraph 0049, (2020/05/29)
The invention discloses a method for preparing organic carboxylic ester by combined catalysis of an aryl bidentate phosphine ligand. The method comprises the following steps: under the action of a palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, carrying out a hydrogen esterification reaction on terminal olefin, carbon monoxide and alcohol so as to generate theorganic carboxylic ester with one more carbon than olefin. According to the invention, by adoption of the palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, good catalytic activity and selectivity for the hydrogen esterification reaction of the olefin are achieved, and olefin carbonylation to synthesize organic carboxylic ester can be efficiently catalyzed. Thearyl bidentate phosphine ligand has a rigid skeleton structure of a rigid ligand and the flexibility of a flexible ligand, so the aryl bidentate phosphine ligand has proper flexibility due to the characteristic that the aryl bidentate phosphine ligand is soft and rigid, and a most favorable coordination mode and a stable active structure in space are favorably formed. In addition, the aryl bidentate phosphine ligand has the advantages of high stability, simple and convenient synthesis method and the like; and a novel industrial technology is provided for production of organic carboxylate compounds.
Synthesis and Applications of Unquaternized C-Bound Boron Enolates
Ng, Elvis Wang Hei,Low, Kam-Hung,Chiu, Pauline
, p. 3537 - 3541 (2018/03/21)
A general and facile method to prepare unquaternized C-bound boron enolates by a ligand-controlled O-to-C isomerization is reported. Using this protocol, C-bound pinacolboron enolates have been isolated in pure form for the first time, and have been fully characterized by NMR spectroscopy and X-ray crystallography. In contrast to the general perception, such C-boron enolates are stable without coordinative saturation at the boron. Moreover, C-boron enolates present reactivities that are distinct from the O-boron enolates, and their applications in C-O and C-C bond formations are demonstrated.
Facile synthesis of 2-aryl or β,γ-unsaturated esters via 1,2-Migration from aryl or α,β-unsaturated ketones using thallium(III) p-tosylate
Lee, Jae In
, p. 125 - 128 (2017/06/07)
The experiment reports that 2-aryl esters can be efficiently synthesized via 1,2-aryl migration from aryl ketones using thallium(III) p-tosylate in high yields. To determine optimum conditions for conversion of aryl ketones to 2-aryl esters, the effects of solvents were examined. An initial reaction of 4'-methoxypropiophenone and perchloric acid using thallium(III) p-tosylate in ethanol afforded ethyl 2-(4-methoxyphenyl)propanoate in only 10% yield after 24 h at room temperature. However, the corresponding reaction in ethanol/triethyl orthoformate (4/1) was completed in 1 h between 0 °C and room temperature to give ethyl 2-(4-methoxyphenyl)propanoate in 94% yield. The presence of triethyl orthoformate induced rapid ketalization of enol intermediate and facilitated 1,2-migration of the 4-methoxyphenyl group. The relative effectiveness of several metal salts was also examined for conversion of 2',4'-dimethoxypropiophenone to ethyl 2-(2,4-dimethoxyphenyl)propanoate. The solvents were evaporated off under reduced pressure, and the residue was dissolved in methylene chloride. The white precipitate was filtered off, and the resulting yellow solution was poured into saturated NaHCO3 solution and extracted with methylene chloride. The combined organic layers were dried over anhydrous MgSO4, filtered, and concentrated in vacuo. The residue was purified by vacuum distillation using a Kugelrohr apparatus to give 4g as a colorless liquid.
Imidazole derivatives as accelerators for ruthenium-catalyzed hydroesterification and hydrocarbamoylation of alkenes: Extensive ligand screening and mechanistic study
Konishi, Hideyuki,Muto, Takashi,Ueda, Tsuyoshi,Yamada, Yayoi,Yamaguchi, Miyuki,Manabe, Kei
, p. 836 - 845 (2015/03/14)
Imidazole derivatives are effective ligands for promoting the [Ru3(CO)12]-catalyzed hydroesterification of alkenes using formates. Extensive ligand screening was performed to identify 2-hydroxymethylated imidazole as the optimal ligand. Neither carbon monoxide gas nor a directing group was required, and the reaction also showed a wide substrate generality. The Ru-imidazole catalyst system also promoted intramolecular hydrocarbamoylation to afford lactams. A Ru-imidazole complex was unambiguously analyzed by X-ray crystallography, and it had a trinuclear structure derived from one [Ru3(CO)12] and two ligands. This complex was also successfully used for hydroesterification. The mechanism was examined in detail by using D- and 13C-labeled formates, indicating that the hydroesterification reaction proceeds by a decarbonylation-recarbonylation pathway. Effective imidazole assistant: [Ru3(CO)12]-catalyzed hydroesterification of alkenes by using formates is drastically accelerated by imidazole derivatives and exhibits a broad substrate scope for both alkenes and formates. The Ru-imidazole complex also catalyzes the intramolecular hydrocarbamoylation of alkenes.
A versatile synthesis of O-desmethylangolensin analogues from methoxy-substituted benzoic acids
Hong, Hyo Jeong,Lee, Jae In
, p. 569 - 574 (2015/02/05)
The synthesis of O-desmethylangolensin (O-DMA) analogues from methoxy-substituted benzoic acids was described. Treatment of methoxy-substituted benzoic acids with 2 equiv of ethyllithium afforded methoxypropiophenones, which were subsequently transformed to ethyl 2-(methoxyphenyl)propionates via 1,2-rearrangement of the methoxyphenyl group using Pb(OAc)4/HClO4 in triethyl orthoformate. After hydrolysis with KOH, the 2-(methoxyphenyl)propionic acids were reacted with di- 2-pyridyl carbonate to afford 2-pyridyl 2-(methoxyphenyl)propionates, which were acylated with methoxy-substituted phenylmagnesium bromides to give methoxy-α-methyldesoxybenzoins. The methoxy groups of these compounds were selectively or fully demethylated using boron tribromide to give diverse O-DMA analogues in high yields.
Pd-catalyzed decarboxylative cross-couplings of potassium malonate monoesters with aryl halides
Feng, Yi-Si,Wu, Wei,Xu, Zhong-Qiu,Li, Yan,Li, Ming,Xu, Hua-Jian
, p. 2113 - 2120 (2012/03/26)
An efficient catalytic protocol for Pd-catalyzed decarboxylative cross-coupling of potassium malonate monoesters and derivatives with aryl bromides and chlorides are described. Because of its broad applicability, this new catalytic system provides an alternative method for the preparation of diverse aryl acetic acids and derivatives.
Hiyama reactions of activated and unactivated secondary alkyl halides catalyzed by a nickel/norephedrine complex
Strotman, Neil A.,Sommer, Stefan,Fu, Gregory C.
, p. 3556 - 3558 (2008/02/14)
(Chemical Equation Presented) An active partner: Nickel in combination with an amino alcohol ligand (norephedrine) was found to provide the most versatile and efficient catalyst for Hiyama cross-coupling reactions of alkyl electrophiles that has been described to date. Unprecedented Hiyama reactions of activated secondary alkyl bromides were achieved, as were the first Hiyama couplings of (activated) alkyl chlorides (see scheme, X = Br, Cl; HMDS = 1,1,1,3,3,3-hexamethyldisilazane, DMA = N,N-dimethylacetamide).
Facile synthesis of highly congested 1,2-diphosphinobenzenes from bis(phosphine)boronium salts
Yamamoto, Yoshikazu,Koizumi, Toru,Katagiri, Kosuke,Furuya, Yui,Danjo, Hiroshi,Imamoto, Tsuneo,Yamaguchi, Kentaro
, p. 6103 - 6106 (2007/10/03)
(Chemical Equation Presented) Bis(phosphine)boronium salts 3a-c were designed and prepared as key building blocks for the synthesis of highly congested diphosphinobenzenes. The preparation of sterically hindered ortho-phenylene-bridged diphosphines 1a-c was achieved by the reaction of the bis(phosphine)boronium salts 3a-c with difluorobenzenechromium complex 2 and subsequent removal of the BH2 group. The steric nature of diphosphine 1a was revealed in single-crystal X-ray analysis of its Rh complex.
1,2-asymmetric induction in the conjugate addition of organocopper reagents to γ-aryl α,β-unsaturated carbonyl derivatives
Chounan, Yukiyasu,Ono, Yasuo,Nishii, Shinji,Kitahara, Haruo,Ito, Shoei,Yamamoto, Yoshinori
, p. 2821 - 2831 (2007/10/03)
The diastereoselectivity in the conjugate addition of organocopper reagents to γ-aryl α,β-unsaturated carbonyl derivatives 8-14 was investigated. The syn-diastereoselectivity was obtained irrespective of the reagents type in the addition of 8, while the anti-diastereoselectivity was obtained in the addition of 10-14 with RCu and RCu(CN)Li (R=Me and Bu) and the syn-selectivity was produced in the addition of 10-14 with R2CuLi and R2Cu(CN)Li2. The reagent controlled and substrate dependent diastereoselectivity are explained by two different reaction pathways: either π-complex formation or ordinary nucleophilic addition. Reduction potentials of the Michael acceptors and electron donating ability of organocopper reagents control the reaction pathway. (C) 2000 Elsevier Science Ltd.
