72659-45-1Relevant academic research and scientific papers
Tuning the Selectivity of Palladium Catalysts for Hydroformylation and Semihydrogenation of Alkynes: Experimental and Mechanistic Studies
Beller, Matthias,Ge, Yao,Jackstell, Ralf,Jiao, Haijun,Liu, Jiawang,Wei, Duo,Wei, Zhihong,Yang, Ji
, p. 12167 - 12181 (2020/11/27)
Here, we describe a selective palladium catalyst system for chemodivergent functionalization of alkynes with syngas. In the presence of an advanced ligand L2 bearing 2-pyridyl substituent as a built-in base, either hydroformylation or semihydrogenation of diverse alkynes occurs with high chemo- and stereoselectivity under comparable conditions. Mechanistic studies, including density functional theory (DFT) calculations, kinetic analysis, and control experiments, revealed that the strength and concentration of acidic cocatalysts play a decisive role in controlling the chemoselectivity. DFT studies disclosed that ligand L2 not only promotes heterolytic activation of hydrogen similar to frustrated Lewis pair (FLP) systems in the hydrogenolysis step for hydroformylation but also suppresses CO coordination to promote semihydrogenation under strong acid conditions. This switchable selectivity provides a strategy to design new catalysts for desired products.
Stereo-controlledanti-hydromagnesiation of aryl alkynes by magnesium hydrides
Chiba, Shunsuke,Li, Yihang,Ong, Derek Yiren,Pang, Jia Hao,Takita, Ryo,Wang, Bin,Watanabe, Kohei
, p. 5267 - 5272 (2020/06/04)
A concise protocol foranti-hydromagnesiation of aryl alkynes was established using 1?:?1 molar combination of sodium hydride (NaH) and magnesium iodide (MgI2) without the aid of any transition metal catalysts. The resulting alkenylmagnesium intermediates could be trapped with a series of electrophiles, thus providing facile accesses to stereochemically well-defined functionalized alkenes. Mechanistic studies by experimental and theoretical approaches imply that polar hydride addition from magnesium hydride (MgH2) is responsible for the process.
Selective palladium-catalyzed hydroformylation of alkynes to α,β-Unsaturated Aldehydes
Fang, Xianjie,Zhang, Min,Jackstell, Ralf,Beller, Matthias
, p. 4645 - 4649 (2013/05/22)
Atom-efficient: A selective palladium catalyst system is used for the hydroformylation of alkynes (see picture). In this syngas reaction, various alkynes were smoothly transformed to synthetically interesting α,β-unsaturated aldehydes in good yields with high regio- and stereoselectivity. Copyright
Substituent effects on the iodine-catalyzed thermal cyclization of 3,4-diphenylbuta-1,3-dienyl isocyanates: Mechanistic studies
Chuang, Ta-Hsien,Chang, Wei-Yu,Li, Chien-Fu,Wen, Yu-Chia,Tsai, Chia-Chen
, p. 9678 - 9686 (2012/01/05)
The thermal cyclization of 3,4-diphenylbuta-1,3-dienyl isocyanates 1, generated in situ from the corresponding azides, was investigated using iodine as a catalyst. Diphenylpyridinones 2, phenylnaphthalenes 3, and indenes 4 were produced via intramolecular ring closure. The nature of the substituents on the phenyl rings was found to be crucial to the distribution of cyclized products 2 - 4. The mechanism of the reaction is also discussed.
Development and application of a direct vinyl lithiation of cis-stilbene and a directed vinyl lithiation of an unsymmetrical cis-stilbene
Cotter, Juliet,Hogan, Anne-Marie L.,O'Shea, Donal F.
, p. 1493 - 1496 (2008/02/02)
Equation Presented The vinyl deprotonation of cis-stilbene can be readily achieved using s-BuLi in THF at -25°C. The generated 1-lithio-1,2- diphenylethene undergoes an in situ Z-to-E isomerization, and subsequent reaction with electrophiles results in an efficient stereoselective synthesis of trisubstituted alkenes. A directed vinyl lithiation of the unsymmetrical cis-stilbene 2-styryl-phenyl-carbamic acid tert-butyl ester can be achieved regioselectively, thereby expanding this methodology for further synthetic applications in indole chemistry.
New route to o-terphenyls: Application to the synthesis of 6,7,10,11-tetramethoxy-2-(methoxycarbonyl)triphenylene
Brenna, Elisabetta,Fuganti, Claudio,Serra, Stefano
, p. 901 - 904 (2007/10/03)
The hydroxy-o-terphenylcarboxylic acid esters 6a-f have been prepared by benzannulation of the 5,6-diaryl-3-methoxycarbonylhexa-3,5-dienoic acids 5a-f using triethylamine-ethyl chloroformate. The application of this new synthesis of triphenylenes is illus
Regioselective Ring Opening Reactions of 1-Aminocyclopropenes via Carbenium Ion and Carbene Intermediates
Yoshida, Hiroshi,Sano, Hiroe,Ogata, Tsuyoshi,Matsumoto, Kiyoshi
, p. 4341 - 4346 (2007/10/02)
The reaction of 1-(disubstituted amino)-2,3-diphenylcyclopropenium salt with phenyl- and alkylmagnesium halides afforded, regioselectively, 1-aminocyclopropenes in good yields.The reactions of these 1-aminocyclopropenes were studied under acidic and nonacidic conditions to yield regioselective ring-opening products (C2-C3 and C1-C3 bond fissions of the cyclopropene) associated with the carbenium ions and carbene intermediates, respectively.
Reaction of HCo(CO)4 with Methyl 2,3-Diphenyl-2-cyclopropene-1-carboxylate: Synthesis of Methyl t,t-2,3-Diphenyl-c-2-formylcyclopropane-r-1-carboxylate
Nalesnik, Theodore E.,Fish, John G.,Horgan, Steven W.,Orchin, Milton
, p. 1987 - 1990 (2007/10/02)
Reaction of HCo(CO)4 with the diphenylcyclopropene 1 leads to the three possible hydrogenated cyclopropanes but in addition a single hydroformylation product is formed.This aldehyde was synthesized by an unambiguous procedure; it is compound 2, formed by
Homologation of Carbonyl Compounds to Aldehydes with Lithium Bis(ethylenedioxyboryl)methide
Matteson, Donald S.,Moody, Robert J.
, p. 1091 - 1095 (2007/10/02)
Tris(ethylenedioxyboryl)methane reacts with methyllithium at -78 deg C in THF to form lithium bis(ethylenedioxyboryl)methide, which reacts with aldehydes and ketones to form 1-alkene-1-boronic esters.These need not be isolated for efficient oxidation by sodium perborate to the homologated aldehydes, which are easily purified.Systematic investigation of the reaction conditions to optimize yields at each step was undertaken.Possibly hazardous 2:1 aldehyde-hydrogen peroxide adducts were found to form under neutral conditions with dilute (5percent) hydrogen peroxide.Hydrogenperoxide was also found to cause some carbon-carbon bond cleavage during oxidation of alkeneboronic acids.Both problems were avoided by the use of sodium perborate instead.Reaction of lithium bis(ethylenedioxyboryl)methide with benzoyl chloride or methyl benzoate followed by hydrolysis was found to yield acetophenone.A significant error in one previous description of the synthesis of the key starting material, tris(dimethoxyboryl)methane, is noted.
