82045-04-3Relevant articles and documents
Free and immobilized lecitase ultra as the biocatalyst in the kinetic resolution of (E)‐4‐arylbut‐3‐en‐2‐yl esters
Chojnacka, Anna,Drozd, Rados?aw,G?adkowski, Witold,Le?niarek, Aleksandra,Szymańska, Magdalena
, (2020/03/17)
The influence of buffer type, co‐solvent type, and acyl chain length was investigated for the enantioselective hydrolysis of racemic 4‐arylbut‐3‐en‐2‐yl esters using Lecitase Ultra (LU). Immobilized preparations of the Lecitase Ultra enzyme had
Size-Exclusion Borane-Catalyzed Domino 1,3-Allylic/Reductive Ireland–Claisen Rearrangements: Impact of the Electronic and Structural Parameters on the 1,3-Allylic Shift Aptitude
Fegyverneki, Dániel,Kolozsvári, Natália,Molnár, Dániel,Egyed, Orsolya,Holczbauer, Tamás,Soós, Tibor
supporting information, p. 2179 - 2183 (2019/01/04)
The reductive Ireland–Claisen rearrangement through borane-mediated hydrosilylation is reported. The method employs a borane catalyst with a special structural design and affords access to synthetically relevant products with high diastereoselectivity. Depending on electronic and structural parameters, the reaction can be coupled with a 1,3-allylic shift, thus the valence isomer of the Ireland–Claisen product is formed.
Site-Selective α-Alkoxyl Alkynation of Alkyl Esters Mediated by Boryl Radicals
Guo, Ao,Han, Jia-Bin,Zhu, Lei,Wei, Yin,Tang, Xiang-Ying
supporting information, p. 2927 - 2931 (2019/04/17)
A novel method for site-selective C-H functionalization of ethyl acetate mediated by pyridine-boryl radicals is presented, delivering a variety of 4-phenylbut-3-yn-2-yl acetate derivatives under mild conditions. A distinguishing feature of this reaction i
Copper-Catalyzed Highly Stereoselective Trifluoromethylation and Difluoroalkylation of Secondary Propargyl Sulfonates
Gao, Xing,Xiao, Yu-Lan,Wan, Xiaolong,Zhang, Xingang
supporting information, p. 3187 - 3191 (2018/02/26)
It is challenging to stereoselectively introduce a trifluoromethyl group (CF3) into organic molecules. To date, only limited strategies involving direct asymmetric trifluoromethylation have been reported. Herein, we describe a new strategy for direct asymmetric trifluoromethylation through the copper-catalyzed stereospecific trifluoromethylation of optically active secondary propargyl sulfonates. The reaction enables propargylic trifluoromethylation with high regioselectivity and stereoselectivity. The reaction could also be extended to stereospecific propargylic difluoroalkylation. Transformations of the resulting enantiomerically enriched fluoroalkylated alkynes led to a variety of chiral fluoroalkylated compounds, thus providing a useful protocol for applications in the synthesis of fluorinated complexes.
Synthesis of Chiral α,β-Unsaturated γ-Amino Esters via Pd-Catalyzed Asymmetric Allylic Amination
Xia, Chao,Shen, Jiefeng,Liu, Delong,Zhang, Wanbin
, p. 4251 - 4254 (2017/08/23)
A Pd-catalyzed asymmetric allylic amination of 4-substituted 2-acetoxybut-3-enoates with amines has been developed for the regiospecific synthesis of chiral α,β-unsaturated γ-amino esters. The desired chiral aminated products can be obtained in up to 98%
Enantioselective NiH/Pmrox-Catalyzed 1,2-Reduction of α,β-Unsaturated Ketones
Chen, Fenglin,Zhang, Yao,Yu, Lei,Zhu, Shaolin
, p. 2022 - 2025 (2017/02/15)
The enantioselective 1,2-reduction of α,β-unsaturated ketones was achieved using a NiH catalyst in the presence of pinacolborane. This mild process represents a general method to access a wide variety of structurally diverse α-chiral allylic alcohols in excellent yields and enantioselectivity, as well as very high levels of ambidoselectivity for 1,2- over 1,4-reduction. Furthermore, for reactions on a 10 mmol scale, catalyst loadings as low as 0.5 mol % could be employed to deliver product without any detrimental effect on the yield, enantio-, or ambidoselectivity.
Facile synthesis of Z -alkenes via uphill catalysis
Singh, Kamaljeet,Staig, Shannon J.,Weaver, Jimmie D.
, p. 5275 - 5278 (2014/05/06)
Catalytic access to thermodynamically less stable Z-alkenes has recently received considerable attention. These approaches have relied upon kinetic control of the reaction to arrive at the thermodynamically less stable geometrical isomer. Herein, we present an orthogonal approach which proceeds via photochemically catalyzed isomerization of the thermodynamic E-alkene to the less stable Z-isomer which occurs via a photochemical pumping mechanism. We consider two potential mechanisms. Importantly, the reaction conditions are mild, tolerant, and operationally simple and will be easily implemented.
Pd(II)-catalyzed direct olefination of arenes with allylic esters and ethers
Shang, Xiaojie,Xiong, Yun,Zhang, Yuexia,Zhang, Lei,Liu, Zhongquan
supporting information; experimental part, p. 259 - 262 (2012/03/08)
A convenient Pd(II)-catalyzed direct olefination of unactivated arenes with allylic esters and ethers via C-H activation was demonstrated. Under the typical conditions, various aryl-substituted allylic esters and ethers can be prepared. Georg Thieme Verlag Stuttgart - New York.
A simple and efficient method for the allylation of heteroarenes catalyzed by PdCl2
Yuan, Feng-Quan,Sun, Feng-Yi,Han, Fu-She
, p. 6837 - 6842 (2012/08/28)
The PdCl2-catalyzed allylation of heteroarenes is presented. Various heteroarenes including O-, N-, and S-based ones were allylated efficiently with a rich range of allylic acetates in the presence of only 2 mol % of PdCl2, without the need of bases/acids, additives, and external supporting ligands. In addition, the reactions were carried out under mild and simple conditions just by stirring the two reactants and catalyst in CH 2Cl2 at 60 °C. Moreover, the by-product produced was non-toxic acetic acid. Thus, the method presented in this work provides a general, clean, and operationally simple approach for the functionalization of heteroarenes. Finally, a preliminary mechanistic study suggested that the Pd(II) may be reduced in situ by the heteroarenes to Pd(0), which serves as the active metal center to catalyze the following allylations of heteroarenes via a Tsuji-Trost pathway.
Highly enantioselective synthesis of 3-substituted furanones by palladium-catalyzed kinetic resolution of unsymmetrical allyl acetates
Mao, Bin,Ji, Yining,Fananas-Mastral, Martin,Caroli, Giuseppe,Meetsma, Auke,Feringa, Ben L.
, p. 3168 - 3173 (2012/05/05)
Resolving the issue: A near-perfect Pd-catalyzed kinetic resolution of 1,3-disubstituted unsymmetrical allylic acetates uses silyl enol ethers as nucleophiles to access the important 3-substituted-furanone scaffold (see scheme; DACH=diaminocyclohexyl, dba=dibenzylideneacetone). The reaction proceeds under mild conditions and provides the desired products with excellent chemo-, regio-, and enantioselectivity. Copyright
