65792-30-5Relevant academic research and scientific papers
Well-Defined, Versatile and Recyclable Half-Sandwich Nickelacarborane Catalyst for Selective Carbene-Transfer Reactions
Wang, Linghua,Perveen, Saima,Ouyang, Yizhao,Zhang, Shuai,Jiao, Jiao,He, Gang,Nie, Yong,Li, Pengfei
supporting information, p. 5754 - 5760 (2021/03/08)
Catalytic carbene-transfer reactions constitute a class of highly useful transformations in organic synthesis. Although catalysts based on a range of transition-metals have been reported, the readily accessible nickel(II)-based complexes have been rarely used. Herein, an air-stable nickel(II)-carborane complex is reported as a well-defined, versatile and recyclable catalyst for selective carbene transfer reactions with low catalyst loading under mild conditions. This catalyst is effective for several types of reactions including diastereoselective cyclopropanation, epoxidation, selective X?H insertions (X = C, N, O, S, Si), particularly for the unprotected substrates. This represents a rare example of carborane ligands in base metal catalysis.
Silica-supported HClO4 promotes catalytic solvent- and metal-free O-H insertion reactions with diazo compounds
Gallo, Rafael Douglas C.,Burtoloso, Antonio C. B.
, p. 4547 - 4556 (2018/10/17)
Solvent-free O-H insertion reactions in the presence of diazo carbonyl compounds were carried-out in very mild conditions. Unlike the traditional metal-catalysed version, employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Br?nsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O-H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room temperature.
Elevated catalytic activity of ruthenium(II)-porphyrin-catalyzed carbene/nitrene transfer and insertion reactions with n-heterocyclic carbene ligands
Chan, Ka-Ho,Guan, Xiangguo,Lo, Vanessa Kar-Yan,Che, Chi-Ming
supporting information, p. 2982 - 2987 (2014/04/03)
Bis(NHC)ruthenium(II)-porphyrin complexes were designed, synthesized, and characterized. Owing to the strong donor strength of axial NHC ligands in stabilizing the trans Mi￡CRR′/Mi￡NR moiety, these complexes showed unprecedently high catalytic activity towards alkene cyclopropanation, carbene C-H, N-H, S-H, and O-H insertion, alkene aziridination, and nitrene C-H insertion with turnover frequencies up to 1950 min-1. The use of chiral [Ru(D4-Por)(BIMe)2] (1 g) as a catalyst led to highly enantioselective carbene/nitrene transfer and insertion reactions with up to 98 % ee. Carbene modification of the N terminus of peptides at 37 °C was possible. DFT calculations revealed that the trans axial NHC ligand facilitates the decomposition of diazo compounds by stabilizing the metal-carbene reaction intermediate.
Gold (I) catalysis of X-H bond insertions
Mangion, Ian K.,Weisel, Mark
experimental part, p. 5490 - 5492 (2010/10/20)
The utility of gold catalysis for carbene X-H bond insertion chemistry is described for the first time, taking advantage of the unique reactivity of sulfoxonium ylides as metal carbene precursors.
Iridium-catalyzed X-H insertions of sulfoxonium ylides
Mangion, Ian K.,Nwamba, Ikenna K.,Shevlin, Michael,Huffman, Mark A.
supporting information; experimental part, p. 3566 - 3569 (2011/02/22)
Image Persented The unique reactivity of sulfoxonium ylides as a carbene source is described for a variety of X-H bond insertions, taking advantage of a simple, commercially available iridium catalyst. This method has applications in both intra- and intermolecular reactivity, including a practical ring-expansion strategy for lactams. The safety and stability of sulfoxonium ylides recommend them as preferable surrogates to traditional diazo ketones and esters.
Copper(I{cyrillic, ukrainian}) hexafluorophosphate: a dual functional catalyst for three-component reactions of methyl phenyldiazoacetate with alcohols and aldehydes or α-ketoesters
Yue, Yongli,Guo, Xin,Chen, Zhiyong,Yang, Liping,Hu, Wenhao
scheme or table, p. 6862 - 6865 (2009/04/07)
Oxonium ylides in situ generated from methyl phenyldiazoacetate and alcohols in the presence of CuPF6(CH3CN)4 underwent an aldol-type reaction with aldehydes or α-ketoesters in a convergent, three-component fashion to give α-alkoxyl-β-hydroxyl acid derivatives in good yields.
Efficient trapping of oxonium ylides with imines: A highly diastereoselective three-component reaction for the synthesis of β-amino-α-hydroxyesters with quaternary stereocenters
Huang, Haoxi,Guo, Xin,Hu, Wenhao
, p. 1337 - 1339 (2008/03/28)
(Chemical Equation Presented) In one huge stride: The single-step construction of polyfunctionalized compounds with a quaternary stereocenter is possible through a highly diastereoselective multicomponent reaction of phenyldiazoacetates, alcohols, and imi
Investigations on leaving group based intra- versus intermolecular glycoside bond formation
Scheffler, G?tz,Behrendt, Michael E.,Schmidt, Richard R.
, p. 3527 - 3539 (2007/10/03)
Ligation of the glyscosyl donor to the glycossyl acceptor through th eleaving group was performed with the aim of enforcing glycoside bond formation by an intramolecular (1.x)-shift. To this end, systheses of alkoxypropenly (27a and b), and 7-alkoxy-4-oxaheptadienly thioglucopyranoside derivatives (35a, b and d) were carried out. Thier activation with thiophilic systems gave the expected glucopyranosides 5a, b and d in up to high chemical yields, yet modest anomeric control. Competition experiments showed that an intermolecular reaction course is favored in these reactions, although model considerations imply that convenient intramolecular (1,3)-, (1,4)- (1,5)-, and (1,9)-shifts, respectively, of the glycosyl donor to the acceptor are possible.
Carbenes in a Rigid Matrix. Substituent Effects on the Temperature Dependence of α-Carbonylcarbene Reactions
Tomioka, Hideo,Okuno, Hiroshi,Izawa, Yasuji
, p. 1636 - 1641 (2007/10/02)
The temperature dependence of methoxycarbonyl- (1a and b) and benzoyl-carbenes (2a and b) reactions in alcohols has been examined in order to elucidate the scope and limitation of low temperature photolysis as a tool for detecting triplet carbenes.The results reveal that the method cannot be applied to all carbenes but gives important information on the reactivity and/or multiplicity of ground-state carbenes.Low-temperature photolysis of PhCN2CO2Me in an ethanol matrix, for example, resulted in a dramatic increase in C-H insertion products, probably derived from the triplet (1a) via an abstraction-recombination mechanism, at the expense of the singlet product, i.e. the O-H insertion compound, which was shown to be the main product of photolysis at ambient temperature.In marked contrast, (1b) generated in a propan-2-ol matrix at -196 deg C did not result in a major increase in the C-H insertion product.Similar and more contrasting substituent effects on the temperature dependence were observed in the benzoylcarbene system (2).Thus, the Wolff rearrangement of (2a) was almost completely supressed in a rigid matrix at -196 deg C, whereas that of (2b) was not appreciably supressed even at -196 deg C.These differences were explained by considering the effects of the substituent on the ground-state multiplicity of carbene and/or on the relation of the activation energy differences of the singlet and triplet reactions with energy differences between two states.
