126784-39-2Relevant articles and documents
Cobalt-Catalyzed Alkoxycarbonylation of Epoxides to β-Hydroxyesters
Xu, Jian-Xing,Wu, Xiao-Feng
, p. 9907 - 9912 (2019/08/26)
Herein, we developed a new and practical catalytic system for the carbonylative synthesis of β-hydroxyesters. By using simple, cheap, and air-stable cobalt(II) bromide as the catalyst, combined with pyrazole and catalytic amount of manganese, active cobalt complex can be generated in situ and can catalyze various epoxides to give the corresponding β-hydroxyesters in moderate to excellent yields. Mechanism studies indicate that pyrazole plays a crucial role in this reaction. Moreover, with the addition of the catalytic amount of manganese, the active cobalt catalyst can be regenerated, which provides a possibility for reusing the cobalt catalyst.
Bu 4 N + -Controlled Addition and Olefination with Ethyl 2-(Trimethylsilyl)acetate via Silicon Activation
Das, Manas,Manvar, Atul,Fox, Ian,Roberts, Dilwyn J.,O'Shea, Donal F.
supporting information, p. 2401 - 2406 (2017/09/30)
Catalytic Bu 4 NOAc as silicon activator of ethyl 2-(trimethylsilyl)acetate, in THF, was utilized for the synthesis of β-hydroxy esters, whereas employing catalytic Bu 4 NOTMS gave α,β-unsaturated esters. The established reaction conditions were applicable to a diverse range of aromatic, heteroaromatic, aliphatic aldehydes and ketones. Reactions were achieved at room temperature without taking any of the specialized precautions that are in place for other organometallics. A stepwise olefination pathway via silylated β-hydroxy esters with subsequent elimination to form the α,β-unsaturated ester has been demonstrated. The key to selective product formation lies in use of the weaker acetate activator which suppresses subsequent elimination whereas stronger TMSO - activator (and base) facilitates both addition and elimination steps. The use of tetrabutyl ammonium salts for both acetate and trimethylsilyloxide activators provide enhanced silicon activation when compared to their inorganic cation counterparts.
Cobalt carbonyl ionic liquids based on the 1,1,3,3-tetra-alkylguanidine cation: Novel, highly efficient, and reusable catalysts for the carbonylation of epoxides
Zhang, Wei,Han, Feng,Tong, Jin,Xia, Chungu,Liu, Jianhua
, p. 805 - 812 (2017/05/29)
A series of novel cobalt carbonyl ionic liquids based on 1,1,3,3-tetra-alkyl-guanidine, such as [1,1-dimethyl-3,3-diethylguanidinium][Co(CO)4] (3a), [1,1-dimethyl-3,3-dibutylguanidinium][Co(CO)4] (3b), [1,1-dimethyl-3,3-tetramethyleneguanidinium][Co(CO)4] (3c), and [1,1-dimethyl-3,3-pentamethyleneguanidinium] [Co(CO)4] (3d), were synthesized in good yields and were also characterized using infrared spectroscopy, ultraviolet-visible spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, 13C NMR spectroscopy, high–resolution mass spectrometry, differential scanning calorimetry, and thermogravimetric analysis. The four compounds exhibited high thermal and chemical stability. In addition, the catalytic performance of these compounds was investigated in the carbonylation of epoxides, with 3a exhibiting the best catalytic activity without the aid of a base as the additive. The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate. Moreover, the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl, alkenyl, aryl, alkoxy, and chloromethyl functional groups.
1,1,3,3-tetra alkyl guanidine carbonyl cobalt metal organic ion liquid and preparation method and application thereof
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Paragraph 0054, (2017/08/31)
The invention discloses a 1,1,3,3-tetra alkyl guanidine carbonyl cobalt metal organic ion liquid. A structure formula of the ion liquid is shown in the description. The invention also discloses a preparation method of the ion liquid and application of the ion liquid in synthesizing of 3-hydroxy carboxylate by epoxy compound hydroesterification. The 1,1,3,3-tetra alkyl guanidine carbonyl cobalt metal organic ion liquid has the advantages that guanidine cation has the double functions of stabilizing tetra carbonyl cobalt cation and using as a Lewis acid to activate epoxy compound primer; compared with the traditional Co2(CO)8/azacycle catalytic system, the use of a nitrogen-containing organic matter is avoided; the ion liquid can be recycled and repeatedly used, the use rate of carbonyl cobalt is improved, and the production cost is reduced; the stability of the 1,1,3,3-tetra alkyl guanidine carbonyl cobalt metal organic ion liquid is high, the ion liquid can be repeatedly applied to catalysis of epoxy compound hydroesterification for multiple times, the catalytic reaction effect is good, and the separation and recycling are convenient.
A concise synthesis of Hagen's gland lactones
Lone, Ali Mohd,Bhat, Bilal Ahmad,Shah, Wajaht Amin,Mehta, Goverdhan
, p. 3610 - 3612 (2014/06/23)
A short synthesis of Hagen's gland lactones 1 and 2 from commercially available pentanal and heptanal, respectively, is outlined. The approach relies on sequential ring closing metathesis and intramolecular oxy-Michael addition as the key transformations.
Cobalt oxide supported gold nanoparticles as a stable and readily-prepared precursor for the in situ generation of cobalt carbonyl like species
Hamasaki, Akiyuki,Muto, Akiko,Haraguchi, Shingo,Liu, Xiaohao,Sakakibara, Takanori,Yokoyama, Takushi,Tokunaga, Makoto
supporting information; experimental part, p. 6869 - 6872 (2012/02/05)
A treatment of cobalt oxide supported gold nanoparticles (Au/Co 3O4) under syngas atmosphere effectively generated a cobalt carbonyl-like active species in the reaction vessel. The preparation of Au/Co3O4 was quite simple and the in situ generated cobalt species could be used as a stable and easy handling alternative for dicobalt octacarbonyl without bothersome purification prior to use. The reactions, which are sensitive to the purity of the dicobalt octacarbonyl, such as the alkoxycarbonylation of epoxides and the Pauson-Khand reaction, smoothly progressed with Au/Co3O4.
Temporary silicon connection strategies in intramolecular allylation of aldehydes with allylsilanes
Beignet, Julien,Jervis, Peter J.,Cox, Liam R.
, p. 5462 - 5475 (2008/12/21)
(Chemical Equation Presented) Three γ-(amino)silyl-substituted allylsilanes 14a-c have been prepared in three steps from the corresponding dialkyldichlorosilane. The aminosilyl group has been used to link this allylsilane nucleophile to a series of β-hydroxy aldehydes through a silyl ether temporary connection. The size of the alkyl substituents at the silyl ether tether governs the outcome of the reaction on exposure to acid. Thus, treatment of aldehyde (E)-9aa, which contains a dimethylsilyl ether connection between the aldehyde and allylsilane, with a range of Lewis and Bronsted acid activators provides an (E)-diene product. The mechanism of formation of this undesired product is discussed. Systems containing a sterically more bulky diethylsilyl ether connection react differently: thus in the presence of TMSOTf and a Bronsted acid scavenger, intramolecular allylation proceeds smoothly to provide two out of the possible four diastereoisomeric oxasilacycles, 23 (major) and 21 (minor). A diene product again accounts for the remaining mass balance in the reaction. This side product can be completely suppressed by using a sterically even more bulky diisopropylsilyl ether connection in the cyclization precursor, although this is now at the expense of a slight erosion in the 1,3-stereoinduction in the allylation products. The sense of 1,3-stereoinduction observed in these intramolecular allylations has been rationalized by using an electrostatic argument, which can also explain the stereochemical outcome of a number of related reactions. Levels of 1,4-stereoinduction in the intramolecular allylation are more modest but can be significantly improved in some cases by using a tethered (Z)-allylsilane in place of its (E)-stereoisomer. Oxidation of the major diastereoisomeric allylation product 23 under Tamao-Kumada conditions provides an entry into stereodefined 1,2-anti-2,4-syn triols 28.
Synthesis of isotetronic acids by cyclization of 1,3-bis(trimethylsilyloxy) alk-1-enes with oxalyl chloride
Dede, Rüdiger,Michaelis, Lars,Langer, Peter
, p. 8129 - 8131 (2007/10/03)
Isotetronic acids were regioselectively prepared by cyclization of 1,3-bis(trimethylsilyloxy)alk-1-enes with oxalyl chloride.
