- Mechanistic insight into the synergistic Cu/Pd-catalyzed carbonylation of aryl iodides using alcohols and dioxygen as the carbonyl source
-
Pd-catalyzed carbonylation, as an efficient synthetic approach to the installation of carbonyl groups in organic compounds, has been one of the most important research fields in the past decade. Although elegant reactions that allow highly selective carbonylations have been developed, straightforward routes with improved reaction activity and broader substrate scope remain long-term challenges for new practical applications. Here, we show a new type of synergistic Cu/Pd-catalyzed carbonylation reaction using alcohols and dioxgen as the carbonyl sources. A broad range of aryl iodides and alcohols are compatible with this protocol. The reaction is concise and practical due to the ready availability of the starting materials and the scalability of the reaction. In addition, the reaction affords lactones and lactams in an intermolecular fashion. Moreover, DFT calculations have been performed to study the detailed mechanisms. [Figure not available: see fulltext.]
- Li, Junxuan,Zhou, Jinlei,Wang, Yumei,Yu, Yue,Liu, Qiang,Yang, Tilong,Chen, Huoji,Cao, Hua
-
-
- Esterification of Tertiary Amides: Remarkable Additive Effects of Potassium Alkoxides for Generating Hetero Manganese–Potassium Dinuclear Active Species
-
A catalyst system of mononuclear manganese precursor 3 combined with potassium alkoxide served as a superior catalyst compared with our previously reported manganese homodinuclear catalyst 2 a for esterification of not only tertiary aryl amides, but also tertiary aliphatic amides. On the basis of stoichiometric reactions of 3 and potassium alkoxide salt, kinetic studies, and density functional theory (DFT) calculations, we clarified a plausible reaction mechanism in which in situ generated manganese–potassium heterodinuclear species cooperatively activates the carbonyl moiety of the amide and the OH moiety of the alcohols. We also revealed details of the reaction mechanism of our previous manganese homodinuclear system 2 a, and we found that the activation free energy (ΔG≠) for the manganese–potassium heterodinuclear complex catalyzed esterification of amides is lower than that for the manganese homodinuclear system, which was consistent with the experimental results. We further applied our catalyst system to deprotect the acetyl moiety of primary and secondary amines.
- Akiyama, Shoko,Himo, Fahmi,Hirai, Takahiro,Katayama, Shoichiro,Kato, Daiki,Mai, Binh Khanh,Mashima, Kazushi,Nagae, Haruki
-
supporting information
(2020/07/25)
-
- A Straightforward Conversion of Activated Amides and Haloalkanes into Esters under Transition-Metal-Free Cs 2 CO 3 /DMAP Conditions
-
The esterification of activated amides, N -acylsaccharins, under transition-metal-free conditions with good functional group tolerance has been developed, resulting in C-N cleavage leading to efficient synthesis of a variety of esters in moderate to good yields. This work demonstrates that esterification may proceed by using simple N -acylsaccharins, haloalkanes, and Cs 2 CO 3 as oxygen source.
- Chen, Liuqing,Gu, Ying,Jian, Junsheng,Liu, Yueping,Miao, Liqiong,Wang, Zijia,Zeng, Zhuo
-
supporting information
p. 4078 - 4084
(2019/10/28)
-
- Synthesis of Esters from Stable and Convenient Sulfoxonium Precursors under Catalyst- And Additive-Free Conditions
-
A convenient and efficient procedure for the construction of esters from stable sulfoxonium ylides and alcohols has been developed. This protocol presents a broad substrate scope and good yields of the desired esters can be isolated. Notably, no catalyst, oxidant, base or any other additive is required.
- Wu, Xiao-Feng,Yuan, Yang
-
p. 1820 - 1824
(2019/09/09)
-
- Palladium-Catalyzed Alkoxycarbonylation of Arylsulfoniums
-
Alkoxycarbonylation of arylsulfoniums has been developed with the aid of a catalytic amount of a palladium-Xantphos complex under an atmospheric pressure of CO gas. Various functional groups such as carbonyl, cyano, halo, and sulfonyl groups were well tolerated under the present catalysis. Since aryldimethylsulfoniums were readily prepared from the corresponding aryl methyl sulfides and methyl triflate, one-pot alkoxycarbonylation of aryl methyl sulfides could be accomplished.
- Minami, Hiroko,Nogi, Keisuke,Yorimitsu, Hideki
-
supporting information
p. 2518 - 2522
(2019/04/17)
-
- Dinuclear manganese alkoxide complexes as catalysts for C-N bond cleavage of simple tertiary: N, N -dialkylamides to give esters
-
Amide bonds are stable due to the resonance between the nitrogen lone pair and the carbonyl moiety, and therefore the chemical transformation of amides, especially tertiary amides, involving C-N bond fission is considered one of the most difficult organic reactions, unavoidably requiring harsh reaction conditions and strong acids or bases. We report the catalytic C-N bond cleavage of simple tertiary N,N-dialkylamides to give corresponding esters using a catalyst system (2 mol% based on Mn atoms) of a tetranuclear manganese alkoxide, [Mn(acac)(OEt)(EtOH)]4 (1c), combined with four equivalents of 4,7-bis(dimethylamino)-1,10-phenanthroline (L1: Me2N-Phen). Regarding the reaction mechanism, we isolated a dinuclear manganese complex, [Mn(acac)(OEt)(Phen)]2 (6c), which was revealed as the catalytically active species for the esterification of tertiary amides.
- Nagae, Haruki,Hirai, Takahiro,Kato, Daiki,Soma, Shusei,Akebi, Shin-Ya,Mashima, Kazushi
-
p. 2860 - 2868
(2019/03/13)
-
- Dehydrogenative cross-coupling of primary alcohols to form cross-esters catalyzed by a manganese pincer complex
-
Base-metal-catalyzed dehydrogenative cross-coupling of primary alcohols to form cross-esters as major products, liberating hydrogen gas, is reported. The reaction is catalyzed by a pincer complex of earth-abundant manganese in the presence of catalytic base, without any hydrogen acceptor or oxidant. Mechanistic insight indicates that a dearomatized complex is the actual catalyst, and indeed this independently prepared dearomatized complex catalyzes the reaction under neutral conditions.
- Das, Uttam Kumar,Ben-David, Yehoshoa,Leitus, Gregory,Diskin-Posner, Yael,Milstein, David
-
p. 479 - 484
(2019/01/11)
-
- Aerobic oxidative esterification and thioesterification of aldehydes using dibromoisocyanuric acid under mild conditions: No metal catalysts required
-
A practical direct method for the direct preparation of esters and thioesters from aldehydes is described. Esters and thioesters were synthesized by oxidative esterification and thioesterification via in situ generated acyl bromide intermediates, which were used to react with various alcohols and thiols. The esterification and thioesterification were readily performed in the presence of dibromoisocyanuric acid in dichloromethane, without any metal catalysts and under mild conditions. By using this reaction protocol, various esters and thioesters were prepared in high yields. This effective method offers a promising approach for the facile esterification and thioesterification of aldehydes.
- Kwon, Young-Do,La, Minh Thanh,Kim, Hee-Kwon
-
p. 10833 - 10841
(2018/07/05)
-
- Room Temperature Carbonylation of (Hetero) Aryl Pentafluorobenzenesulfonates and Triflates using Palladium-Cobalt Bimetallic Catalyst: Dual Role of Cobalt Carbonyl
-
An efficient method for the carbonylation of (hetero) aryl pentafluorobenzenesulfonates and triflates under exceptionally mild conditions using palladium/dicobalt octacarbonyl [Pd/Co2(CO)8] has been developed. Besides acting as carbon monoxide (CO) source, Co2(CO)8enhances the reaction rate by accelerating the CO insertion through an in situ generated bimetallic palladium cobalt tetracarbonyl [Pd-Co(CO)4] complex. Under the optimized reaction condition, carbonylation of a wide range of activated and deactivated, as well as sterically hindered and heteroaromatic, substrates proceeded efficiently at room temperature. The high chemoselectivity and improved synthesis of biologically relevant Isoguvacine and Lazabemide intermediates highlights its scope as a valuable synthetic method. The generality of this protocol was further extended to other electrophiles (bromides, chlorides and tosylates). (Figure presented.).
- Joseph, Jayan T.,Sajith, Ayyiliath M.,Ningegowda, Revanna C.,Shashikanth, Sheena
-
p. 419 - 425
(2017/02/10)
-
- Practical: In situ -generation of phosphinite ligands for palladium-catalyzed carbonylation of (hetero)aryl bromides forming esters
-
An effective method for alkoxycarbonylation of (hetero)aryl bromides is developed in the presence of in situ-generated phosphinite ligands tBu2POR (R = nBu, nPr, Et or Me). For this purpose commercially available tBu2PCl was used as the pre-ligand in the presence of different alcohols. For the first time cross coupling reactions with two alcohols-one generating the ligand, the other used as substrate-were developed. Through this method, ligand optimization can be performed in a more efficient manner and the desired products could be obtained with good yields and selectivity.
- Wang, Lin,Neumann, Helfried,Spannenberg, Anke,Beller, Matthias
-
supporting information
p. 7469 - 7472
(2017/07/12)
-
- Deuterodechlorination of Aryl/Heteroaryl Chlorides Catalyzed by a Palladium/Unsymmetrical NHC System
-
The catalytic deuterodechlorination of aryl/heteroaryl chlorides was developed with a palladium/unsymmetrical NHC system, and the precisely controlled introduction of deuterium into a variety of aryl/heteroaryl compounds was achieved with a high level of efficiency, selectivity, and deuteration degree. This method was also successfully applied to the transformation of bioactive agents even in a gram-scale synthesis. The crystal structure analysis of Pd-NHC complexes led to the observation of Pd-arene interaction.
- Kuriyama, Masami,Hamaguchi, Norihisa,Yano, Gemba,Tsukuda, Kotaro,Sato, Kanako,Onomura, Osamu
-
p. 8934 - 8946
(2016/10/14)
-
- Fe-Catalyzed Aerobic Oxidative C-CN Bond Cleavage of Arylacetonitriles Leading to Various Esters
-
Fe-catalyzed aerobic oxidative esterifications of arylacetonitriles with alcohols, tri alkoxsilanes, silicate esters, or borate esters have been developed. The acyl groups which were in situ generated via chemoselective C(CO)-CN bond cleavage were directly used as electrophiles, leading to corresponding aryl esters in good to excellent yields under molecular oxygen when attacked by alcohols or alcohol surrogates. Dioxygen serves as both oxidant and reactant in this protocol. The reaction has a very broad substrate scope. Cheap starting materials as well as environmentally benign and inexpensive iron catalyst and ideal oxidant O2 feature this transformation and make it a practical and sustainable protocol to afford esters.
- Kong, Weiguang,Li, Bingnan,Xu, Xuezhao,Song, Qiuling
-
p. 8436 - 8443
(2016/09/28)
-
- From ketones to esters by a Cu-catalyzed highly selective C(CO)-C(alkyl) bond cleavage: Aerobic oxidation and oxygenation with air
-
The Cu-catalyzed aerobic oxidative esterification of simple ketones via C-C bond cleavage has been developed. Varieties of common ketones, even inactive aryl long-chain alkyl ketones, are selectively converted into esters. The reaction tolerates a wide range of alcohols, including primary and secondary alcohols, chiral alcohols with retention of the configuration, electron-deficient phenols, as well as various natural alcohols. The usage of inexpensive copper catalyst, broad substrate scope, and neutral and open air conditions make this protocol very practical. 18O labeling experiments reveal that oxygenation occurs during this transformation. Preliminary mechanism studies indicate that two novel pathways are mainly involved in this process. (Chemical Equation Presented)
- Huang, Xiaoqiang,Li, Xinyao,Zou, Miancheng,Song, Song,Tang, Conghui,Yuan, Yizhi,Jiao, Ning
-
supporting information
p. 14858 - 14865
(2014/12/11)
-
- Transition metal-free oxidative esterification of benzylic alcohols in aqueous medium
-
Oxidative esterification of benzylic alcohols with a catalytic amount of HBr-H2O2 in aqueous medium under mild conditions is reported with a wide range of substrate scope for both benzylic and aliphatic alcohols. The conditions are also suitable for selective mono-esterification of ethylene glycol and glycerol. With catalytic amounts of HBr (20 mol%) and H2O2, the generation of reactive intermediate species BrOH has been ascertained by UV-visible spectra.
- Samanta, Supravat,Pappula, Venkatanarayana,Dinda, Milan,Adimurthy, Subbarayappa
-
supporting information
p. 9453 - 9456
(2014/12/11)
-
- Generally applicable and efficient esterification of aldehydes with alcohols catalyzed by cyclopalladated ferrocenylimine
-
The palladacycle-catalyzed esterification of a variety of aldehydes with alcohols was developed. This reaction allows formation of esters in moderate to excellent yields not only for various aldehydes but also alcohols. In addition, the esterification could proceed well under mild conditions with a low catalyst loading of 0.0625 mol%. Copyright
- Ma, Gaizhi,Leng, Yuting,Qiao, Huijie,Yang, Fan,Wang, Shiwei,Wu, Yangjie
-
-
- Fe3O4 supported Pd(0) nanoparticles catalyzed alkoxycarbonylation of aryl halides
-
This paper describes the simple and efficient method for the alkoxycarbonylation of aryl iodides using magnetically recoverable Pd/Fe 3O4 as the catalyst under atmospheric pressure of carbon monoxide. Various aryl iodides on alkoxycarbonylation with alcohols gave the corresponding products in good to excellent yields. The catalyst is completely recoverable with the simple application of an external magnetic field, and the efficiency of the catalyst remains unaltered even after five cycles.
- Siva Prasad, Aviraboina,Satyanarayana, Bollikonda
-
p. 205 - 209
(2013/04/23)
-
- Ligand free palladium catalyzed decarboxylative cross-coupling of aryl halides with oxalate monoester salts
-
Ligand free Pd-catalyzed decarboxylative cross-coupling of potassium oxalate monoester and derivatives with aryl iodides and bromides is described. Functionalized aromatic esters can be efficiently synthesized via this method with only 1.0 mol % Pd(OAc)2 catalyst without any phosphine ligand. This method illustrates an inexpensive and operationally simple method for the preparation of aromatic esters and acids, which is especially beneficial for a large scale synthesis.
- Li, Yan,Chen, Huan-Huan,Wang, Chu-Fei,Xu, Xiao-Lan,Feng, Yi-Si
-
p. 5796 - 5799
(2012/10/29)
-
- Mechanistic investigation of oxidation of some substituted aromatic acetals with N-bromosuccinimide in acetonitrile medium - A kinetic approach
-
The oxidation of meta- and para-substituted aromatic acetals by N-bromosuccinimide (NBS) to the corresponding esters and alkyl bromide, is first-order in [NBS] and [acetal]. The effect of substituents in the aromatic ring of some aromatic acetals [X-C6H4CH(OBu-B) 2] {X = H, p-OMe, p-Me, p-Cl, p-NO2, m-OMe, m-CI, m-NO2} on the kinetics of above oxidation has been studied in acetonitrile medium at various temperatures by iodometric method. The rate of the reaction increases with the increase in the dielectric constant of the medium. The stoichiometry of the reaction is found to be 1 : 1. A primary kinetic isotopic effect kH/kD of 1.8 is observed, which indicates the C-H bond cleavage of the aldehydic carbon in the rate determining step. The Hammett reaction constant (a) for the reaction is found to be -1.38 and -1.42 at 313 K and 323 K respectively. The Exner plot is found to be linear with the isokinetic temperature 132 K. The kinetic and activation parameters Ea, A, ΔH≠, ΔG≠ and ΔS≠ have been calculated. A mechanism involving simultaneous loss of H+ from the aldehydic carbon and expulsion of bromide ion with the formation of carbonium ion intermediate is proposed.
- Mathiyalagan
-
p. 1499 - 1506
(2013/02/23)
-
- Efficient carbonylation of aryl and heteroaryl bromides under atmospheric pressure of CO
-
In the presence of Et and n-BuOH, efficient alkoxycarbonylation of (hetero)aromatic bromides was achieved under atmospheric pressure of carbon monoxide with in situ generated palladium/rac-BINAP as catalyst. Georg Thieme Verlag Stuttgart - New York.
- Yang, Weizhun,Han, Wei,Zhang, Weidong,Shan, Lei,Sun, Jiansong
-
supporting information; experimental part
p. 2253 - 2255
(2011/10/19)
-
- Correlation analysis in the study of oxidation kinetics of aromatic acetals with N-bromosuccinimide in acetonitrile medium
-
An attempt has been made to correlate the rate constants of substituted acetals with the chemical shifts of the benzylic proton of the acetals (log k2 vs δ). This correlation is similar to that of which is obtained between σ vs δ. The benzylic proton chemical shift in acetals is found to be the characteristics of acetals. The benzylic proton does not couple with other protons and hence appears as a singlet, which would ensure effective correlation.
- Mathiyalagan
-
scheme or table
p. 865 - 868
(2012/04/10)
-
- Palladium-catalyzed aerobic oxidative carbonylation of arylboronate esters under mild conditions
-
(Figure Presented) "CO"n Air: The title reaction was carried out using [PdCl2(PPh3)2 ] as the catalyst precursor under very mild conditions (balloon pressure of CO and air, at 40- 50°C), and produced a wide range of aryl carboxyl esters 2 in good to excellent yields. Remarkable selectivity between oxidative carbonylation and homocoupling of arylboronate esters l was also achieved.
- Liu, Qiang,Li, Gang,He, Jun,Liu, Jing,Li, Peng,Lei, Aiwen
-
supporting information; experimental part
p. 3371 - 3374
(2010/07/06)
-
- The first general and selective palladium(II)-catalyzed alkoxycarbonylation of arylboronates: Interplay among benzoquinone-ligated palladium(0) complex, organoboron, and alcohol solvent
-
Methoxycarbonylation of aryl- and alken-ylboron compounds was performed using the palladium (II) acetate/triphenylphosphine [PdACHTUNGTRENNUNG(OAc) 2/PPh3] catalyst with p-benzoquinone as a stoichiometric oxidant in methanol at ambient temperature to obtain the corresponding methyl esters in good yields. A wide variety of functional groups including various carbonyl functionalities, nitrile, nitro, sulfone, and unprotected pyrrole rings were tolerated in the methoxycarbonlation, while the use of higher alcohols except for tert-butanol afforded various pchlorobenzoates in moderate to high yields. The catalytic alkoxycarbonylation proceeded without any acid or base additive, and an oxidative transmetalation step is proposed to explain the exceptional efficacy of this protocol. DFT and MP2 calculations support the proposed mechanism.
- Yamamoto, Yoshihiko
-
supporting information; experimental part
p. 478 - 492
(2010/07/03)
-
- Protic acid immobilized on solid support as an extremely efficient recyclable catalyst system for a direct and atom economical esterification of carboxylic acids with alcohols
-
(Chemical Equation Presented) A convenient and clean procedure of esterification is reported by direct condensation of equimolar amounts of carboxylic acids with alcohols catalyzed by an easy to prepare catalyst system of perchloric acid immobilized on silica gel (HClO4-SiO2). The direct condensation of aryl, heteroaryl, styryl, aryl alkyl, alkyl, cycloalkyl, and long-chain aliphatic carboxylic acids with primary/secondary alkyl/cycloalkyl, allyl, propargyl, and long-chain aliphatic alcohols has been achieved to afford the corresponding esters in excellent yields. Chiral alcohol and N-t-Boc protected chiral amino acid also resulted in ester formation with the representative carboxylic acid or alcohol without competitive N-t-Boc deprotection and detrimental effect on the optical purity of the product demonstrating the mildness and chemoselectivity of the procedure. The esters of long-chain (>C10) acids and alcohols are obtained in high yields. The catalyst is recovered and recycled without significant loss of activity. The industrial application of the esterification process is demonstrated by the synthesis of prodrugs of ibuprofen and a few commercial flavoring agents. Other protic acids such as H2SO4, HBr, TfOH, HBF4, and TFA that were adsorbed on silica gel were less effective compared to HClO4-SiO2 following the order HClO4-SiO 2 ? H2SO4-SiO2 > HBr-SiO 2 > TfOH-SiO2 ? HBF4-SiO2 ≈ TFA-SiO2. When HClO4 was immobilized on other solid supports the catalytic efficiency followed the order HClO4-SiO 2 > HClO4-K10 > HClO4-Al 2O3 (neutral) > HClO4-Al2O 3 (acidic) > HClO4-Al2O3 (basic).
- Chakraborti, Asit K.,Singh, Bavneet,Chankeshwara, Sunay V.,Patel, Alpesh R.
-
supporting information; experimental part
p. 5967 - 5974
(2009/12/24)
-
- Copper-catalyzed synthesis of esters from ketones. Alkyl group as a leaving group
-
The conversion of ketones to esters has been achieved through the use of Cu catalyst and tetrabutylammonium nitrite. This reaction involves the activation of the less activated C-C bond, and the alkyl group is removed as a leaving group. Various isopropyl ketones are found to be good substrates for this reaction.
- Nakatani, Yuji,Koizumi, Yuichiro,Yamasaki, Ryu,Saito, Shinichi
-
supporting information; experimental part
p. 2067 - 2070
(2009/04/08)
-
- Transesterification of various methyl esters under mild conditions catalyzed by tetranuclear zinc cluster
-
(Chemical Equation Presented) A new catalytic transesterification promoted by a tetranuclear zinc cluster was developed. The mild reaction conditions enabled the reactions of various functionalized substrates to proceed in good to high yield. A large-scale reaction under solvent-free conditions proceeded with a low E-factor value (0.66), indicating the high environmental and economical advantage of the present catalysis.
- Iwasaki, Takanori,Maegawa, Yusuke,Hayashi, Yukiko,Ohshima, Takashi,Mashima, Kazushi
-
p. 5147 - 5150
(2008/09/21)
-
- A simple procedure for the esterification of alcohols with sodium carboxylate salts using 1-tosylimidazole (TsIm)
-
An efficient and selective method for esterification of alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, alcohols are refluxed with a mixture of RCO2Na (R: alkyl and aryl), TsIm, and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in DMF to afford the corresponding esters in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.
- Soltani Rad, Mohammad Navid,Behrouz, Somayeh,Faghihi, Mohammad Ali,Khalafi-Nezhad, Ali
-
p. 1115 - 1120
(2008/09/17)
-
- Copper-catalyzed oxidative esterification of alcohols with aldehydes activated by Lewis acids
-
An efficient oxidative esterification of aromatic and aliphatic aldehydes with simple alcohols was accomplished using catalytic amounts of Cu(ClO4)2·6H2O and InBr3 with tert-hydroperoxide as an oxidant.
- Yoo, Woo-Jin,Li, Chao-Jun
-
p. 1033 - 1035
(2008/02/05)
-
- Efficient carbonylation of aryl and heteroaryl bromides using a palladium/diadamantylbutylphosphine catalyst
-
A general palladium-catalyzed alkoxycarbonylation of aryl and heteroaryl bromides has been developed in the presence of bulky monodentate phosphines. Studies of the butoxycarbonylation of three model substrates revealed the advantages of di-1-adamantyl-n-butylphosphine compared to other ligands. In the presence of this catalyst system various bromoarenes provided the corresponding benzoic acid derivatives (ester, amides, acids) in excellent yield at low catalyst loadings (0.5 mol% Pd or below).
- Neumann, Helfried,Brennfuehrer, Anne,Gross, Peter,Riermeier, Thomas,Almena, Juan,Beller, Matthias
-
p. 1255 - 1261
(2007/10/03)
-
- Alumina sulfuric acid as a novel heterogeneous system for esterification of carboxylic acids in solvent free conditions
-
Neat chlorosulfonic acid reacts with alumina to give alumina sulfuric acid (ASA) in which sulfuric acid is immobilised on the surface of alumina via a covalent bond. Carboxylic acids can be readily converted to their corresponding esters with a combination of ASA and alcohols in solvent free conditions.
- Sharghi, Hashem,Sarvari, Mona Hosseini,Eskandari, Razieh
-
p. 488 - 491
(2007/10/03)
-
- Linear free energy relationship and conformational effects on oxidation of aromatic acetals by pyridinium fluorochromate
-
Kinetics of oxidation of aromatic acetals by pyridiniumfluorochromate (PFC) in aqueous acetic acid medium reveal that the reactions are second order, first order each in [acetal] and [PFC]. The presence of electron- withdrawing substituents in the benzene ring enhances the rate of oxidation while that of opposite one retards it. The small ρ value suggests a mechanism with little charge separation. The rate of oxidation depends on the nature of alkyl group and conformational effects.
- Ramakrishnan,Nambi
-
p. 232 - 234
(2007/10/03)
-
- Fe2(SO4)3·xH2O in synthesis: A convenient and efficient catalyst for the esterification of aromatic carboxylic acids with alcohols
-
Fe2(SO4)3·xH2O has been used for the catalyst in the esterification of aromatic carboxylic acids with alcohols. The method offers mild reaction condition, easy work-up, and high yields of the esterification products.
- Zhang, Gui-Sheng
-
p. 607 - 611
(2007/10/03)
-
- Activity of substituted and unsubstituted bezaldehydes in reaction with butyl hypochlorite
-
Substituted benzaldehydes under daylight react with butyl hypochlorite affording the corresponding butyl benzoates. Electron-donating substituents in the benzene ring of the aldehyde accelerate, and the electron-withdrawing one decelerate the reaction. The yields of the substituted butyl benzoates in all cases are lower than that of bytyl benzoate.
- Bikbulatov,Zorin,Zorina,Rakhmankulov
-
p. 1633 - 1635
(2007/10/03)
-
- A comparison of the reactivity and mutagenicity of n-(benzoyloxy)-n-(benzyloxy)benzamides
-
A new series of N-(acyloxy)-N-alkoxybenzamides, AT-(benzoyloxy)-JV-(benzyloxy)benzamides 7 have been synthesized and have been found to be direct acting mutagens in Salmonella TA100. They undergo AAl1 solvolysis to give N-benzoyl-N-(benzyloxy)nitrenium ions 3 under conditions of acid catalysis as well as unusual BAl2 reactions at nitrogen with hydroxide. The latter process affords as intermediates the anomeric hydroxamic esters 4 which rearrange intramolecularly to esters in a HERON reaction. Rates of acid-catalyzed solvolysis and reaction with hydroxide ions correlate with Hammett σ values with low sensitivity (ρ = +0.32 and +0.55, respectively) in accordance with the AAl1 and BAl2 mechanisms. Mutagenicity for the series also appears to correlate with Hammett σ values but with low, negative sensitivity (p = -0.57), and their biological activity may be attributable to their stability under conditions of the Ames assay and hydrophobic binding to DNA, rather than their chemical reactivity.
- Glover, Stephen A.,Hammond, Gerard P.,Bonin, Antonio M.
-
p. 9684 - 9689
(2007/10/03)
-
- Catalytic processes of oxidation by hydrogen peroxide in the presence of Br2 or HBr. Mechanism and synthetic applications
-
The mechanism and the synthetic applications for the oxidation of alcohols, ethers, and aldehydes by H2O2 catalyzed by Bf2 or Br- in a liquid two-phase system (aqueous and organic) are reported. Aliphatic and benzylic primary alcohols and ethers show an opposite behavior, which has been rationalized on the ground of the different electronic configurations of the intermediate alkyl (π-type) and acyl (σ-type) radicals and their influence on enthalpic and polar effects. A two-phase system is particularly useful also for an efficient benzylic bromination by Br2 or Br-; the substitution of the benzyl bromide by OH, OR, and OCOR regenerates Br-, which can be recycled. The evaluation of the relative reactivities of the involved substrates and intermediates has allowed to develop a variety of simple, facile, convenient, and selective syntheses of alcohols, aldehydes, ketones, esters, and benzyl bromides, which fulfill the conditions for practical applications.
- Amati, Alessandro,Dosualdo, Gabriele,Zhao, Lihua,Bravo, Anna,Fontana, Francesca,Minisci, Francesco,Bjorsvik, Hans-Rene
-
p. 261 - 269
(2013/09/08)
-
- Butoxycarbonylation of aryl halides catalyzed by a silica-supported poly[3-(2-cyanoethylsulfanyl)propylsiloxane palladium] complex
-
Aryl bromides and iodides react with carbon monoxide and n-butyl alcohol at 100°C and atmospheric pressure in the presence of tri-n-butylamine and a catalytic amount of a silica-supported sulfur palladium complex to form esters in moderate to good yields.
- Cai, Ming-Zhong,Song, Cai-Sheng,Huang, Xian
-
p. 2273 - 2274
(2007/10/03)
-
- Hypervalent (tert-butylperoxy)iodanes generate iodine-centered radicals at room temperature in solution: Oxidation and deprotection of benzyl and allyl ethers, and evidence for generation of α-oxy carbon radicals
-
1-(tert-Butylperoxy)-1,2-benziodoxol-3(1H)-one (1a) oxidizes benzyl and allyl ethers to the esters at room temperature in benzene or cyclohexane in the presence of alkali metal carbonates. Since this reaction is compatible with other protecting groups such as MOM, THP, and TBDMS ethers, and acetoxy groups, and because esters are readily hydrolyzed under basic conditions, this new method provides a convenient and effective alternative to the usual reductive deprotection. Oxidation with 1a occurs readily with C-H bonds activated by both enthalpic effects (benzylic, allylic, and propargylic C-H bonds) and/or polar effects (α-oxy C-H bonds), generating α-oxy carbon-centered radicals, which can be detected by nitroxyl radical trapping. Measurement of the relative rates of oxidation for a series of ring-substituted benzyl n-butyl ethers 2d and 2p-s indicated that electron-releasing groups such as p-MeO and p-Me groups increase the rate of oxidation, and Hammett correlation of the relative rate factors with the σ+ constants of substituents afforded the reaction constant ρ+ = -0.30. The large value of the isotope effect obtained for the oxidation of benzyl n-butyl ether 2d (k(H)/k(D) = 12-14) indicates that the rate-determining step of the reactions probably involves a high degree of benzylic C-H bond breaking. The effects of molecular dioxygen were examined, and the mechanism involving the intermediacy of the tert-butylperoxy acetal 5 and/or the hydroperoxy acetal 32 is proposed. Particularly noteworthy is the finding that (tert-butylperoxy)iodane 1a can generate the tert-butylperoxy radical and the iodine-centered radical 33a, even at room temperature in solution, via homolytic bond cleavage of the hypervalent iodine(III)-peroxy bond.
- Ochiai, Masahito,Ito, Takao,Takahashi, Hideo,Nakanishi, Akinobu,Toyonari, Mika,Sueda, Takuya,Goto, Satoru,Shiro, Motoo
-
p. 7716 - 7730
(2007/10/03)
-
- Decomposition of N,N'-Diacyl-N,N'-dialkoxyhydrazines Revisited
-
N,N'-Diacyl-N,N'-dialkoxyhydrazines have been shown to decompose thermally to esters and nitrogen.An intramolecular crossover experiment has shown that the formation of esters is consistent with a three-centred rearrangement process which is characteristic of N-alkoxy N-amino amides.The four-centred mechanism previously proposed by earlier workers is less favourable energetically.AM1 molecular orbital calculations support these experimental findings.
- Buccigross, Jeanne M.,Glover, Stephen A.,Hammond, Gerard P.,Rowbottom, Colleen A.
-
p. 353 - 362
(2007/10/02)
-
- Mild, one-pot conversion of carboxylic acids into esters using phase transfer catalysis
-
One-pot conversion of carboxylic acids into esters under the influence of phase transfer catalysis is reported.The method is shown to work satisfactorily for optically active acids having epimerisable α-hydrogen.
- Puntambekar, Hemalata M,Naik, D G,Kapadi, A H
-
p. 793 - 794
(2007/10/02)
-
- Kinetics and Mechanism of Oxidation of Aromatic Acetals by Ceric Ammonium Nitrate in Acetonitrile Medium
-
Aromatic acetals of benzaldehyde and substituted benzaldehydes with n-butanol have been prepared and subjected to ceric ammonium nitrate oxidation in acetonitrile medium.The oxidation follows a total second order kinetics, first order each in and IV>.Variation in ionic strength of the medium and added nitrate ions have no influence on the rate.Decrease of dielectric constant of the medium decreases the rate.Activation parameters have been computed from Arrhenius plots.Activation enthalpy and entropy of the oxidation are linearly related.Both activation energy and frequency factor have been found to control the reaction.A probable mechanism has been proposed.
- Chockalingam, P.,Ramakrishnan, P. S.,Arulraj, S. J.,Nambi, K.
-
p. 247 - 250
(2007/10/02)
-
- Bimolecular Reactions of Mutagenic N-Acetoxy-N-alkoxybenzamides and N-Methylaniline
-
N-Methylaniline reacts bimolecularly with mutagenic N-acetoxy-N-alkoxybenzamides and the resultant N-alkoxy-N-(N-methylanilino)benzamides undergo a novel, concerted rearrangement to alkylbenzoates and 1-methyl-1-phenyldiazene which dimerizes to 1,4-dimethyl-1,4-diphenyl-tetrazene.
- Campbell, John J.,Glover, Stephen A.
-
p. 1661 - 1663
(2007/10/02)
-
- Substituents Effect on the Reaction of Aromatic Acetals Over Aluminium Phosphate and Aluminium Sulphate Catalyst
-
Aromatic acetals in the presence of aluminium phosphate (AP) catalyst at elevated temperatures yield the corresponding esters (b), ethers (c) and the parent aldehydes (d).These substrates over aluminium sulphate (AS) catalyst give only the esters (b) and aldehydes (d).The products distribution varies with temperature.Substituents in the ring also play a part in the reaction.
- Xavier, N.,Arulraj, S. J.
-
p. 775 - 777
(2007/10/02)
-
- Chromic Acid Oxidation of Aromatic Acetals in Aqueous Acetic Acid Medium. A Kinetic and Mechanistic Study
-
When aromatic acetals of benzaldehyde and substituted-benzaldehyde with aliphatic alcohols are subjected to chromic acid oxidation in aqueous acetic acid medium, the corresponding esters are the main products.The oxidation follows a total second order kinetics, first order each in and VI>.The decrease of solvent polarity increases the rate of oxidation.The rate-determining step is assumed to be the elimination of proton from the complex species involving the acetal and chromium.The activation enthalpies and entropies of the oxidation of aromatic acetals are linearly related.
- Nambi, K.,Ahamed, K. A. Basheer,Arulraj, S. J.
-
-
- Kinetic and Thermodynamic Parameters for the Alcoholysis of 2,2,2-Trichloro-1-arylethanones
-
The reactions of 2,2,2-trichloro-1-phenylethanone (1a) and 2,2,2-trichloro-1-(p-chlorophenyl)-ethanone (1b) with MeOH, EtOH, n-PrOH, and n-BuOH in the presence of ethylamine resulted in the formation of the corresponding esters ArCOOR.When the process is carried out in the absence of ethylamine the reaction does not proceed beyond formation of the hemiacetal intermediate.The former reaction occurs through an addition-elimination process and the order of reactivity of the alcohols is MeOH>EtOH>n-PrOH>n-BuOH.If (1a or b) is treated with ethylamine in dioxane the corresponding amide ArCONHEt is the only reaction product.
- Uieara, Marina,Zucco, Cesar,Zanette, Dino,Rezende, Marcos C.,Nome, Faruk
-
p. 175 - 180
(2007/10/02)
-
- REARRANGEMENT OF SUBSTITUTED AROMATIC ACETALS CATALYSED BY γ-ALUMINA
-
Aromatic acetals over γ-alumina undergo rearrangement to give the corresponding esters (b) and ethers (c) in good yield.The product distribution varied unusually over the range of reaction temperatures.The effect of substituents has also been felt much in the study.Probable mechanisms have been suggested for the reaction.The catalyst has been characterized by various studies and the specific poisoning of the catalyst has been done with NH3, CO2 and H2S.
- Xavier, N.,Arulraj, S. J.
-
p. 2875 - 2878
(2007/10/02)
-