- Cobalt-Catalyzed Acceptorless Dehydrogenation of Alcohols to Carboxylate Salts and Hydrogen
-
The facile oxidation of alcohols to carboxylate salts and H2 is achieved using a simple and readily accessible cobalt pincer catalyst (NNNHtBuCoBr2). The reaction follows an acceptorless dehydrogenation pathway and displays good functional group tolerance. The amine-amide metal-ligand cooperation in cobalt catalyst is suggested to facilitate this transformation. The mechanistic studies indicate that in-situ-formed aldehydes react with a base through a Cannizzaro-type pathway, resulting in potassium hemiacetolate, which further undergoes catalytic dehydrogenation to provide the carboxylate salts and H2
- Gunanathan, Chidambaram,Kishore, Jugal,Pattanaik, Sandip,Pradhan, Deepak Ranjan
-
supporting information
(2020/03/03)
-
- Method for synthesizing cyclobutyl formic acid
-
The invention relates to a method for synthesizing cyclobutyl formic acid. The method is characterized by comprising the following steps: dissolving acrylic acid into halogenated hydrocarbon, coolingto minus 70 DEG C to minus 10 DEG C, slowly introducing an ethylene gas, performing lighting catalysis by an ultraviolet lamp, sampling a GC (Gas Chromatograph) central control raw material, removingacrylic acid, and completing reactions so as to obtain a reaction liquid; performing normal pressure distillation on the reaction liquid, removing a solvent, and performing vacuum distillation, thereby obtaining a finished product, namely a cyclobutyl formic acid liquid which is colorless to light yellow, wherein the introduction speed of an ethylene gas is 100-250 ml/minute, the introduction timeis 2.5-5 hours, the pressure of vacuum distillation is -0.09 to -0.06 MPa, the temperature is 70-110 DEG C, halogenated hydrocarbon is dichloromethane, trichloromethane or 1,2-dichloroethane, the amount of halogenated hydrocarbon is 1-20 times of the weight of the acrylic acid, the amount of the introduced ethylene gas is 0.5-1.2 times of the weight of the acrylic acid, and the ultraviolet lamp is a 250-450W ultraviolet high-voltage mercury lamp. The method has the advantages that the purity of the finished product is improved, industrial production is easily achieved, the cost is low, and the environment is protected.
- -
-
Paragraph 0009; 0010-0012
(2018/04/15)
-
- Synthesis method of analgesic intermediate bromomethyl cyclobutane
-
The invention relates to a synthesis method of analgesic intermediate bromomethyl cyclobutane. The synthesis method comprises the following steps: by taking ethylene and acrylic acid as starting materials, carrying out Diels-Alder reaction to obtain cyclobutanecarboxylic acid, then reducing to obtain cyclobutanemethanol, and then brominating to obtain high-purity bromomethyl cyclobutane, wherein the total yield reaches more than 65%. The synthesis method provided by the invention has the advantages of available raw materials, mild reaction conditions, simple postprocessing operation, small environmental pollution, short reaction time, high reaction operational safety, high reaction yield, good product quality and low cost, and industrial production is facilitated.
- -
-
Paragraph 0009; 0010; 0011; 0012; 0013; 0014
(2017/07/21)
-
- Carboxylation of Aromatic and Aliphatic Bromides and Triflates with CO2 by Dual Visible-Light–Nickel Catalysis
-
We report the efficient carboxylation of bromides and triflates with K2CO3 as the source of CO2 in the presence of an organic photocatalyst in combination with a nickel complex under visible light irradiation at room temperature. The reaction is compatible with a variety of functional groups and has been successfully applied to the synthesis and derivatization of biologically active molecules. In particular, the carboxylation of unactivated cyclic alkyl bromides proceeded well with our protocol, thus extending the scope of this transformation. Spectroscopic and spectroelectrochemical investigations indicated the generation of a Ni0 species as a catalytic reactive intermediate.
- Meng, Qing-Yuan,Wang, Shun,K?nig, Burkhard
-
supporting information
p. 13426 - 13430
(2017/10/07)
-
- Gold-catalyzed cycloisomerization of 1,7-enyne esters to structurally diverse cis -1,2,3,6-tetrahydropyridin-4-yl ketones
-
A synthetic method that relies on gold(I)-catalyzed cycloisomerization of 1,7-enyne esters to prepare highly functionalized cis-1,2,3,6-tetrahydropyridin- 4-yl ketone derivatives in good to excellent yields and as a single regio-, diastereo-, and enantiomer is described. By taking advantage of the distinctive differences in the electronic and steric properties between an NHC (NHC = N-heterocyclic carbene) and phosphine ligand in the respective gold(I) complexes, a divergence in product selectivity was observed. In the presence of [PhCNAuIPr]+SbF6- (IPr = 1,3-bis(2,6- diisopropylphenyl)imidazol-2-ylidine) as the catalyst, tandem 1,3-acyloxy migration/6-exo-trig cyclization/1,5-acyl migration of the substrate was found to selectively occur to give the δ-diketone-substituted 1,2,3,6-tetrahydropyridine adduct. In contrast, reactions with the gold(I) phosphine complex [MeCNAu(JohnPhos)]+SbF6- (JohnPhos = (1,1′-biphenyl-2-yl)-di-tert-butylphosphine) as the catalyst was discovered to result in preferential 1,3-acyloxy migration/6-exo-trig cyclization/hydrolysis of the 1,7-enyne ester and formation of the cis-1,2,3,6-tetrahydropyridin-4-yl ketone derivative. The utility of this piperidine forming strategy as a synthetic tool that makes use of 1,7-enyne esters was exemplified by its application to the synthesis of an enantiopure analogue of the bioactive 2,3,4,4a,5,9b-hexahydroindeno[1,2-c]pyridine family of compounds.
- Rao, Weidong,Sally,Koh, Ming Joo,Chan, Philip Wai Hong
-
p. 3183 - 3195
(2013/06/27)
-
- The structural basis for the narrow substrate specificity of an acetyl esterase from Thermotoga maritima
-
Acetyl esterases from carbohydrate esterase family 7 exhibit unusual substrate specificity. These proteins catalyze the cleavage of disparate acetate esters with high efficiency, but are unreactive to larger acyl groups. The structural basis for this distinct selectivity profile is unknown. Here, we investigate a thermostable acetyl esterase (TM0077) from Thermotoga maritima using evolutionary relationships, structural information, fluorescent kinetic measurements, and site directed mutagenesis. We measured the kinetic and structural determinants for this specificity using a diverse series of small molecule enzyme substrates, including novel fluorogenic esters. These experiments identified two hydrophobic plasticity residues (Pro228, and Ile276) surrounding the nucleophilic serine that impart this specificity of TM0077 for small, straight-chain esters. Substitution of these residues with alanine imparts broader specificity to TM0077 for the hydrolysis of longer and bulkier esters. Our results suggest the specificity of acetyl esterases have been finely tuned by evolution to catalyze the removal of acetate groups from diverse substrates, but can be modified by focused amino acid substitutions to yield enzymes capable of cleaving larger ester functionalities.
- Hedge, Matthew K.,Gehring, Alexandra M.,Adkins, Chinessa T.,Weston, Leigh A.,Lavis, Luke D.,Johnson, R. Jeremy
-
experimental part
p. 1024 - 1030
(2012/09/05)
-
- Benzothiadiazine compounds
-
Compound of formula (I): wherein: R1 represents hydroxy, RCO—O— or RCO—NRa—, R2 represents hydrogen, halogen, or hydroxy, R′CO—O or R′CO—NR′a—, R and R′, which may be identical or different, represent linear or branched (C1-C6)alkyl optionally substituted by aryl, linear or branched (C2-C6)alkenyl optionally substituted by aryl, linear or branched (C1-C6)perhaloalkyl, (C3-C7)cycloalkyl, adamantyl, aryl or heteroaryl, Ra and R′a, which may be identical or different, represent hydrogen or linear or branched (C1-C6)alkyl, linear or branched (C1-C6)perhaloalkyl, linear or branched (C1-C6)acyl, aryl or heteroaryl, its isomer and addition salts thereof with a pharmaceutically acceptable acid or base and medicinal products containing the same are useful as AMPA modulators.
- -
-
-
- Selenium-catalyzed oxidations with aqueous hydrogen peroxide. 2. Baeyer-Villiger reactions in homogeneous solution
-
Several diselenides were tested for catalytic activity in Baeyer-Villiger reactions with 60% aqueous hydrogen peroxide. Bis[3,5-bis(trifluoromethyl)phenyl] diselenide forms the corresponding 3,5-bis-(trifluoromethyl)benzene seleninic acid in situ, which is a highly reactive and selective catalyst for the oxidation of carbonyl compounds in 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,2-trifluoroethanol, or dichloromethane.
- Ten Brink,Vis,Arends,Sheldon
-
p. 2429 - 2433
(2007/10/03)
-
- Correlation of rates of uncatalyzed and hydroxide-ion catalyzed ketene hydration. A mechanistic application and solvent isotope effects on the uncatalyzed reaction
-
Rates of hydration of a number of ketenes were measured in neutral and basic solution using flash photolytic techniques, and rate constants for their uncatalyzed, k(uc), and hydroxide-ion catalyzed, k(HO), reactions were determined. These results, plus additional data from the literature, were found to provide the remarkably good correlation log k(uc) = -3.21 + 1.14 log k(HO), which spans 10 orders of magnitude in reactivity and includes 31 ketenes. This good correlation implies that uncatalyzed and hydroxide-ion catalyzed ketene hydraton occur by similar reaction mechanisms, which for the hydroxide-ion catalyzed process is known to involve nucleophilic attack on the carbonyl carbon atom of the ketene. Rate constants for phenylhydroxyketene, on the other hand, do not fit this correlation, which suggests that the mechanistic assignment upon which these rate constants are based may not be correct. Solvent isotope effects on these uncatalyzed ketene hydrations are weak; most are less than k(H)/k(D) = 2. It is argued that these isotope effects are largely, if not entirely, secondary in nature and that they are consistent with both a reaction mechanism in which nucleophilic attack of a single water molecule on the ketene carbonyl carbon atom produces a zwitterionic intermediate and also a mechanism that avoids this intermediate by passing through a cyclic transition state involving several water molecules.
- Andraos, John,Kresge, A. Jerry
-
p. 508 - 515
(2007/10/03)
-
- Oxidative ring contraction of cycloalkanones: A facile metrod for synthesis of medium ring cycloalkanecarboxylic acids
-
Cycloalkanones (1) oxidized with 30% hydrogen peroxide in the presence of poly(bisanthracenyl) diselenide (5b) as catalyst, produce cycloalkanecarboxylic acids (2) having one carbon atom less in the ring that the substrate. Although preparative yield of acids 2 does not exceed 60% the reaction can be applied as a simple way for synthesis of cycloalkanecarboxylic acids with five to seven-membered ring.
- Giurg, Miroslaw,Mlochowski, Jacek
-
p. 2281 - 2291
(2007/10/03)
-
- Unusual products from dirhodium tetraacetylate-catalyzed decomposition of diazoacetylcycloalkanes
-
Rh2(OAc)4-assisted decompositions of diazoacetylcycloalkanes are shown to yield cycloalkylacetic acids (Wolff rearrangement), unexpected cycloalkylcarboxylic acids and bicyclic ketones (intramolecular C-H bond insertion). Rh2(OCOF3)4-promoted reactions, on the other hand, have furnished bicyclic ketones and ketene dimers.
- Ceccherelli, Paolo,Curini, Massimo,Marcotullio, Maria Carla,Pisani, Emanuela,Rosati, Ornelio,Wenkert, Ernest
-
p. 8501 - 8506
(2007/10/03)
-
- Favorski type rearrangement in the lead tetraacetate oxidation of cycloalkanones
-
The cycloalkanones (1a-1f) have been converted into their corresponding cycloalkane carboxylates (2a-2f) by a lead(IV) acetate promoted rearrangement in presence of perchloric acid in triethyl orthoformate.
- Mathew, Felix,Myrboh, Bekington
-
p. 1097 - 1101
(2007/10/03)
-
- Use of malonic acid derivative compounds for retarding plant growth
-
This invention relates to a method for retarding plant growth by applying to the plant an effective amount of a malonic acid derivative compound. This invention also relates to novel malonic acid derivative compounds and processes for the preparation thereof.
- -
-
-
- General Synthesis of Methyl- and Dimethyl-cyclobutanes from Simple 1,3-Diols by Phase Transfer Catalysis
-
A general method is described for the preparation of methyl- and dimethyl-cyclobutanes from simple 1,3-diols.The key steps of the procedure are a phase transfer catalysed ring closure and the transformation of a carboxyl group to a methyl group.Phase transfer catalysis provides good yields in the synthesis of the cyclobutane skeleton.
- Toeroek, Bela,Molnar, Arpad
-
p. 801 - 804
(2007/10/02)
-
- Carbacyclins, process for the preparation thereof, and use thereof as medicinal agents
-
The invention relates to carbacyclins of general Formula I STR1 wherein R1 is the residue CH2 OH or STR2 with R2 meaning a hydrogen atom, an alkyl, cycloalkyl, aryl residue, a STR3 or heterocyclic residue, or R1 is the residue STR4 with R3 meaning an alkanoyl or alkanesulfonyl residue of respectively 1-10 carbon atoms or the residue R2, or R1 is the residue STR5 wherein m is the number 1 or 2, X is an oxygen atom or a CH2 -group, A is a trans--CH=CH- or -- C--group, W is a free or functionally modified hydroxymethylene group wherein the OH-group can be in the α- or β- position, n is the number 1, 2, or 3, D is a straight-chain alkylene group of 1-5 carbon atoms, E is a --C C---bond or a --CR6 =CR7 --group wherein R6 and R7 are different from each other and mean a hydrogen atom or an alkyl group of 1-5 carbon atoms or a hydrogen atom or a halogen atom, preferably chlorine, R4 is an alkyl, cycloalkyl, or optionally substituted arly group, or a heterocyclic group, R5 is a free or functionally modified hydroxy group, and if R2 means a hydrogen atom, the salts thereof with physiologically compatible bases; to processes for the preparation thereof, and to the use thereof as blood-pressure-lowering agents.
- -
-
-
- Synthesis and Liquid Crystal Properties of Dimethylene Linked Compounds Incorporating the Cyclobutane or Spiroheptane Rings
-
The preparation of sixteen dimethylene linked compounds is described heptane ring>, and a comparison is made between the transition temperatures of these compounds and those of the corresponding esters.This comparison once again highlights the fact that the cyclobutane ring should be regarded, in terms of its ability to promote nematic thermal stability, as a "chain stiffener rather than as a ring system.A comparison is also made of the nematic thermal stabilities of the trans-cyclobutane and the spiroheptane systems and of the trans-cyclohexane and the spiroundecane systems.
- Chan, L. K. M.,Gemmell, P. A.,Gray, G. W.,Lacey, D.,Toyne, K. J.
-
p. 229 - 246
(2007/10/02)
-
- ANALYSE STRUCTURALE EN SERIE CYCLOBUTANIQUE. Partie 1. Derives monosubstitues et gem disubstitues du cyclobutane
-
Methylene bending mode analysis of some cyclobutane-d2 molecules reveals that in the dissolved state (solvent CCl4), bromocyclobutane occurs exclusively in a pseudo-equatorial form, whereas, under the same conditions, cyclobutanol and 1-bromocyclobutane carbonitrile exist both in pseudo-axial and pseudo-equatorial conformations.NMR spectroscopy confirms the results obtained for bromocyclobutane and leads to the conclusion that the pseudo-equatorial conformer is predominant in the case of cyclobutanol as well as in that of cyclobutane carbonitrile.A theoretical study of cyclobutanol in the gaseous state by the P.C.I.L.O. method gives results which are consistent with a pseudo-equatorial conformer.
- Karimine, Mohamed,Galsomias, Jacqueline,Lere-Porte, Jean-Pierre,Petrissans, Jean
-
p. 321 - 332
(2007/10/02)
-
- Bicyclopentanone. Synthesis, Thermal Chemistry, and Photochemistry
-
Bicyclopentanone (1) has been prepared in two steps, the key reaction being the ozonolysis of 2-phenylbicyclopentan-2-ol (6).On heating, 1 undergoes cycloreversion to allylketene (13).The activation parameters and solvent effects for this process suggest that the reaction is concerted and that the transition state is relatively nonpolar.The predominant photochemical pathway for 1 is decarbonylation to bicyclobutane (16).Cycloreversion to 13 is a minor reaction mode.Both the thermal and photochemical results are rationalized by considering the high strain energy and novel geometrical features of 1, and, in the latter case, the unusually high energy of its 1(n?excit.) state.
- Sponsler, Michael B.,Dougherty, Dennis A.
-
p. 4978 - 4984
(2007/10/02)
-
- Degenerate Carbon Skeleton Isomerization of the Cyclopentyl Cation in the Gas Phase. Experimental and Theoretical Evidence for the Existence of a Pyramidal C5H9(+) Cation as an Intermediate in the Unimolecular Ethylene Elimination
-
The investigation of 13C2-labelled isotopomeric bromocyclopentanes (5a, b), cyclobutylmethyl bromide (6a) and 5-bromo-1-pentenes (7a, b) clearly demonstrates, that unimolecular ethylene loss from the gaseous + ions generated from both the cyclic and acyclic precursors is preceded by complete carbon scrambling.Whereas the degenerate isomerization 8a 8b can, in principle, proceed either via the bisected cyclobutylmethyl cation 9 or via the non-classical, pyramidal cation 3, the MINDO/3 calculations reveal, that ethylene loss from C5H9+ involves 3 as an intermediate.From 3 a transition state is reached which can be regarded as a partially opened cyclopropyl cation "solvated" by interaction with C2H4.Descriptions of the syntheses of the 13C2-labelled bromides are given.
- Franke, Wilfried,Schwarz, Helmut,Thies, Helga,Chandrasekhar, Jayaraman,Raque' Schleyer, Paul von,et al.
-
p. 2808 - 2824
(2007/10/02)
-
