7203-46-5Relevant academic research and scientific papers
Direct Acetoxylation of Arenes
Hong Nguyen, Thi Anh,Hou, Duen-Ren
supporting information, p. 8127 - 8131 (2021/08/23)
Acetoxylation of arenes is an important reaction and an unmet need in chemistry. We report a metal-free, direct acetoxylation reaction using sodium nitrate under an anhydrous environment of trifluoroacetic acid, acetic acid, and acetic anhydride. Arenes (31 examples), with oxidation potentials (Eox, in V vs SCE) lower than benzene (2.48 V), were acetoxylated with good yields and regioselectivity. A stepwise, single electron-transfer mechanism is proposed.
Regioselective Baeyer-Villiger oxidation of lignin model compounds with tin beta zeolite catalyst and hydrogen peroxide
Jennings, John A.,Parkin, Sean,Munson, Eric,Delaney, Sean P.,Calahan, Julie L.,Isaacs, Mark,Hong, Kunlun,Crocker, Mark
, p. 25987 - 25997 (2017/07/07)
Lignin depolymerization represents a promising approach to the sustainable production of aromatic molecules. One potential approach to the stepwise depolymerization of lignin involves oxidation of the benzylic alcohol group in β-O-4 and β-1 linkages, followed by Baeyer-Villiger oxidation (BVO) of the resulting ketones and subsequent ester hydrolysis. Towards this goal, BVO reactions were performed on 2-adamantanone, a series of acetophenone derivatives, and lignin model compounds using a tin beta zeolite/hydrogen peroxide biphasic system. XRD, 119Sn MAS NMR spectroscopy, DRUVS and XPS were used to determine tin speciation in the catalyst, the presence of both framework Sn and extra framework SnO2 being inferred. Conversion of ketones to BVO products was affected by electron donation as well as steric hindrance, 4′-methoxyacetophenone affording the highest yield of ester (81%). As the size and complexity of the ketone increased, excess hydrogen peroxide was typically needed for successful BVO. Yields of ester products derived from β-O-4 and β-1 lignin models were modest due to the formation of polymeric material stemming from direct ring hydroxylation.
The Baeyer-Villiger oxidation versus aromatic ring hydroxylation: Competing organic peracid oxidation mechanisms explored by multivariate modelling of designed multi-response experiments
Gambarotti, Cristian,Bj?rsvik, Hans-René
, p. 619 - 628 (2015/09/28)
Peroxy acids can be used as the terminal oxidant for the Baeyer-Villiger oxidation of acetophenones and for direct ring hydroxylation of methoxy-substituted benzenes. An oxidative system involving 3-chloroperbenzoic acid (mCPBA) and 2,6-dimethoxyacetophenone as model substrate was investigated by means of statistical experimental design, multivariate modelling and response surface methodology. The outcome of the organic peracid oxidation experiments was portrayed by a multi-response matrix consisting of the yields of three different compounds; 2,6-dimethoxyphenyl acetate, 1-(4-hydroxy-2,6-dimethoxy-phenyl)ethanone and 3-hydroxy-2,6-dimethoxy-phenyl acetate. The optimized reaction protocol was utilized to investigate a series of various substituted acetophenones. The overall investigation revealed that both the molecular structure of the acetophenone substrate and the experimental conditions exhibited a substantial impact on whether the oxidation reaction follows the oxygen insertion or direct ring hydroxylation mechanism. An improved protocol for the direct ring hydroxylation was also obtained from the experimental and modelling described herein.
Porous coordination polymers of diverse topologies based on a twisted tetrapyridylbiaryl: Application as nucleophilic catalysts for acetylation of phenols
Seth, Saona,Venugopalan, Paloth,Moorthy, Jarugu Narasimha
, p. 2241 - 2249 (2015/01/30)
Porous coordination polymers (CPs) with partially uncoordinated pyridyl rings based on rationally designed polypyridyl linkers are appealing from the point of view of their application as nucleophilic catalysts. A D2d--symmetric tetradentate organic linker L, that is, 2,2 ',6,6'-tetramethoxy-3,3',5,5'-tetrakis(4-pyridyl)biphenyl, was designed and synthesized for metal-assisted self-assembly aimed at porous CPs. Depending on the nature of the metal ion and the counter anion, the ligand L is found to function as a 3- or 4-connecting building block leading to porous CPs of diverse topologies. The reaction of L with Zn(NO3)2 and Cd(NO3)2 yields porous 2D CPs of "fes" topology, in which the tetrapyridyl linker L serves as a 3-connecting unit with its free pyridyl rings well exposed into the pores. The functional utility of these porous CPs containing uncoordinated pyridyl rings is demonstrated by employing them as efficient heterogeneous nucleophilic catalysts for acetylation of a number of phenols with varying electronic properties and reactivities.
Rh-Catalyzed Synthesis of Coumarin Derivatives from Phenolic Acetates and Acrylates via C-H Bond Activation
Gadakh, Sunita K.,Dey, Soumen,Sudalai, Arumugam
, p. 11544 - 11550 (2015/12/04)
An efficient annulation strategy involving the reaction of phenolic acetates with acrylates in the presence of [Rh2(OAc)4] as catalyst and formic acid as reducing agent, leading to the high yield synthesis of coumarin derivatives, has been developed. The addition of NaOAc as a base increased the yield of the products. The reaction is quite successful for both electron-rich as well as electron-deficient phenolic acetates, affording coumarins with excellent regioselectivity, and proceeds via C-H bond activation proven by deuterium incorporation studies.
Steric control of site selectivity in the Pd-catalyzed C-H acetoxylation of simple arenes
Cook, Amanda K.,Emmert, Marion H.,Sanford, Melanie S.
supporting information, p. 5428 - 5431 (2013/11/19)
This report describes the use of an oxidant and a ligand to control site selectivity in the Pd(OAc)2-catalyzed C-H acetoxylation of simple arenes. The use of MesI(OAc)2 as the terminal oxidant in combination with acridine as the ligand results in primarily sterically controlled selectivity. In contrast, with Pd(OAc)2 as the catalyst and PhI(OAc)2 as the oxidant, electronic effects dominate the selectivity of arene C-H acetoxylation.
Direct oxidation of secondary alcohol to ester by performic acid
Li, Xiao-Hong,Meng, Xiang-Guang,Liu, Ying,Peng, Xiao
, p. 3332 - 3336 (2013/12/04)
The reaction pathways and kinetics of the oxidation reactions of 1-phenylethyl alcohol (PEA), 1-(3,4-dimethoxyphenyl)ethanol (MVA), 1-(4-hydroxy-3-methoxyphenyl)ethanol (HMOPE), 1-(3-aminophenyl)ethanol (APE), 1-(4-methylphenyl)ethanol (MPE) and cyclohexanol with performic acid (PFA) were investigated in formic acid solvent. An unexpected new reaction pathway, from which the secondary alcohols can be directly oxidized to corresponding esters, was found. The reaction products (esters and ketones) of oxidation of PEA, MVA, HMOPE, APE, MPE and cyclohexanol were detected at different reaction times. The reaction rate constants, k1, k2, k3 and power orders α, β, γ of PFA concentration for three oxidation reactions pathways: alcohol to ester, alcohol to ketone and ketone to ester were obtained, respectively. These findings might provide a new insight into the technology of lignin degradation.
Palladium-catalyzed acetoxylation of arenes by novel sulfinyl n-heterocyclic carbene ligand complexes
Tato, Francisco,Garcia-Dominguez, Andres,Cardenas, Diego J.
supporting information, p. 7487 - 7494 (2014/04/03)
A series of novel ligands based on N-heterocyclic carbene and sulfoxide functionalities have been prepared and characterized. Pd(II) complexes have been synthesized by transmetalation from the corresponding NHC-Ag derivatives, and their behavior as catalysts has been studied in arene C-H bond oxidative activation. Studies conducted toward the elucidation of the reaction mechanism of the acetoxylation suggest a C-H activation step at Pd(IV) rather than Pd(II) intermediates.
Theoretical and experimental studies on selective oxidation of aromatic ketone by performic acid
Liu, Bo,Meng, Xiang-Guang,Li, Wei-Yi,Zhou, Liang-Chun,Hu, Chang-Wei
scheme or table, p. 2920 - 2926 (2012/05/20)
The Baeyer-Villiger (B-V) reactions of 3,4-dimethoxy acetophenone (DMOAP), 4-methyl acetophenone (MAP), and acetophenone (AP) with performic acid (PFA) in formic acid (FA) solvent have been studied by density functional theory (DFT) method. The noncatalyzed and the formic acid-catalyzed reaction paths have been calculated at the MPWB1K/6-311++G(d,p)-IEF-PCM// MPWB1K/6-311G(d,p) level of theory. On the basis of the calculations, the attack of peracid to the carbonyl carbon is rate-determining in both the noncatalyzed and acid-catalyzed paths. The selective oxidation of 3,4-dimethoxy acetophenone and 4-methyl acetophenone by performic acid into aromatic esters have been experimentally investigated. The kinetic rate constants were obtained in the temperature range of 303 to 323 K. The selectivity of product was also explained by the NBO electric charge analysis. The calculated activation energy barriers of the B-V reaction of DMOAP and MAP were in good agreement with those of experiment.
New approach for the construction of the coumarin frame and application in the total synthesis of natural products
Jerezano, Alberto,Jimenez, Fabiola,Del Carmen Cruz, Maria,Montiel, Luisa E.,Delgado, Francisco,Tamariz, Joaquin
experimental part, p. 185 - 198 (2011/04/17)
A new synthetic approach is described for building the coumarin scaffold through the Lewis acid-promoted cyclization of novel aryl 3-(dimethylamino)prop- 2-enoates 2a - 2f. The latter precursors were prepared via aminomethylenation of the corresponding aryl acetates 4a - 4f with the Bredereck reagent. This approach was used for the synthesis of biologically active natural compounds 1a - 1f, through a three-step procedure starting from the corresponding phenols.
