148149-45-5Relevant academic research and scientific papers
C?Boron Enolates Enable Palladium Catalyzed Carboboration of Internal 1,3-Enynes
Chrostowska, Anna,Lamine, Walid,Li, Bo,Liu, Shih-Yuan,Miqueu, Karinne,Sotiropoulos, Jean-Marc,Wang, Ziyong,Wu, Jason
supporting information, p. 21231 - 21236 (2021/09/02)
A new family of carbon-bound boron enolates, generated by a kinetically controlled halogen exchange between chlorocatecholborane and silylketene acetals, is described. These C?boron enolates are demonstrated to activate 1,3-enyne substrates in the presence of a Pd0/Senphos ligand complex, resulting in the first examples of a carboboration reaction of an alkyne with enolate-equivalent nucleophiles. Highly substituted dienyl boron building blocks are produced in excellent site-, regio-, and diastereoselectivity by the described catalytic cis-carboboration reaction.
Palladium catalyzed hydroesterification of substituted alkenes under microwave conditions
Du Plessis, Maretha,Marais, Charlene,Bezuidenhoudt, Barend C. B.
supporting information, p. 40 - 48 (2020/09/16)
While several catalyst systems have been utilized in the hydroesterification or methoxycarbonylation of alkenes or equivalent substrates, these reactions are conventionally performed in autoclave reactor systems under high CO pressure (20-70 bar) and thermal heating (70 - 110 oC). In this paper, the first methoxycarbonylation reactions performed in a microwave reactor fitted with a gas-Addition accessory system are reported on and compared to the same reactions performed under conventional heating in an autoclave reactor. Thus 1-octene, styrene, allylbenzene, o-and p-methoxyallylbenzene and β-methylstyrene were subjected to methoxycarbonylation over a palladium acetate-aluminum triflate catalyst system at 12 bar and 95 oC. Results obtained indicated the methoxycarbonylation of these alkenes to be much faster under microwave conditions when compared to conventional heating and improvements in conversion ranged between 3 and 5% for the more reactive substrates (1-octene and styrene) and 6 - 20% for the allylbenzenes and β-methylstyrene.
Parameters Influencing Reactivity and Regioselectivity in the Methoxycarbonylation of Arylalkenes
Du Plessis, Maretha,Marais, Charlene,Bezuidenhoudt, Barend C. B.
, p. 557 - 565 (2016/02/14)
Previous research showed that the steric bulk, electronic character, and bite angle of the ligand have an influence on both the catalyst activity and regioselectivity of hydroformylation and hydroesterification reactions. However, little is known in this regard about the influence of the steric and electronic environment around the double bond of the substrate. A variety of arylalkenes were therefore subjected to methoxycarbonylation to investigate the steric and electronic effects of substituents on the aromatic ring of the substrate on the regioselectivity and reactivity in the methoxycarbonylation reaction of these substrates with a Pd(II)/Al(OTf)3/Ph3P catalyst system.
Copper-Catalyzed Boron-Selective C(sp2)-C(sp3) Oxidative Cross-Coupling of Arylboronic Acids and Alkyltrifluoroborates Involving a Single-Electron Transmetalation Process
Ding, Siyi,Xu, Liang,Li, Pengfei
, p. 1329 - 1333 (2016/02/18)
A rapid and highly selective oxidative cross-coupling reaction between readily available and shelf-stable arylboronic acids and primary or secondary potassium alkyltrifluoroborates was devised and developed, which works under mild conditions using copper(II) acetate as the catalyst and silver oxide as the oxidant. Initial experimental results indicate that a single-electron transmetalation process is involved. This approach effectively bypasses the problems associated with the traditional cross-coupling reactions of alkylboronates and thus provides a complementary method in building C(sp2)-C(sp3) bonds.
Pd-Catalyzed Regioselective Alkoxycarbonylation of 1-Alkenes Using a Lewis Acid [SnCl2 or Ti(OiPr)4] and a Phosphine
Amézquita-Valencia, Manuel,Achonduh, George,Alper, Howard
, p. 6419 - 6424 (2015/06/30)
The phosphine ligand mediated palladium catalyzed alkoxycarbonylation of alkenes was investigated with the objective of attaining good linear selectivity for the ester. The effect of various parameters such as solvents, additives, palladium precursors, CO pressures, and alkenes of various structural complexities were examined. The results revealed the importance of using a Lewis acid such as SnCl2 or Ti(OiPr)4 in combination with a monodentate ligand such CYTOP 292 or P(p-anisyl)3 to enhance the regioselectivity for the linear isomers in the range of 70-96%.
Chemo- and diastereoselective Bi(OTf)3-catalyzed benzylation of silyl nucleophiles
Rubenbauer, Philipp,Bach, Thorsten
, p. 1305 - 1309 (2008/09/18)
The direct alkylation of silyl enol ethers with para-methoxybenzylic alcohols or their corresponding acetates was efficiently catalyzed by Bi(OTf)3 in CH3NO2 as the solvent. The reaction provided the α-benzylated carbonyl
Sm/HOAc/EtOH system-mediated reduction of Baylis-Hillman acetates
Liu, Yunkui,Mao, Dajie,Xu, Danqian,Xu, Zhenyuan,Zhang, Yongmin
, p. 4389 - 4397 (2008/03/14)
Selective formation of (2E)-2-methylalk-2-enoates or 2-methyl alkanoates could be achieved in moderate to good yields under mild conditions via Sm/HOAc/EtOH system-mediated reduction of Baylis-Hillman acetates depending on the amount of samarium consumed in the reactions. Copyright Taylor & Francis Group, LLC.
Highly regioselective anti-markovnikov palladium-borate-catalyzed methoxycarbonylation reactions: Unprecedented results for aryl olefins
Vieira, Tiago O.,Green, Mike J.,Alper, Howard
, p. 6143 - 6145 (2007/10/03)
(Chemical Equation Presented) A general, highly efficient and regioselective methoxycarbonylation, by means of a palladium-salicylicborate- catalyzed protocol, of terminal alkyl and aryl olefins is described. The substrates include aliphatic alkenes, allylbenzenes, and styrene derivatives. The yields are very good (60-92%) and the regioselectivity, in favor of the linear ester, is up to quantitative - unprecedented in the case of styrenes.
Diastereoselective heterogeneous catalytic hydrogenation of Baylis- Hillman adducts
Mateus, Cristiano R.,Almeida, Wanda P.,Coelho, Fernando
, p. 2533 - 2536 (2007/10/03)
We describe herein our results concerning a highly diastereoselective heterogeneous hydrogenation of Baylis-Hillman adducts obtained from aromatic aldehydes. The results obtained are complementary to those already described for homogeneous catalytic hydro
Free-Radical Coupling of Alkyl and Aryl Halides with Electron-Deficient Alkenes Mediated by Chromium(II) Complexes
Tashtoush, Hasan I.,Sustmann, Reiner
, p. 1759 - 1762 (2007/10/02)
Free radicals generated from organic halides and (ethylenediamine)chromium(II) complexes in DMF are trapped by electron-deficient olefins.The coupling reactions of alkyl halides, described in Part I, are extended and, in addition, aryl halides are shown to be efficient radical precursors to yield coupling products in good yield. Key Words: Bond formation, C-C/ Chromium(II) complexes/ Radicals
