- Iron(III)-zirconium(IV) combined salt immobilized on N-(polystyrylbutyl) pyridinium triflylimide as a reusable catalyst for a dehydrative esterification reaction
-
N-(Polystyrylbutyl)pyridinium triflylimide is prepared by a coupling reaction of commercially available 4-bromobutyl-polystyrene with pyridine and a subsequent anion exchange reaction with lithium triflylimide. This new polystyrene-bound pyridinium salt is useful as a solid support to immobilize a zirconium(IV)-iron(III) binary metal complex, which is a homogeneous catalyst for the dehydrative ester condensation of an equimolar mixture of carboxylic acids and alcohols. The immobilized zirconium(IV)-iron(III) complex is easily recovered by filtration after complete esterification, and is reusable without any loss of activity.
- Nakamura, Yuka,Maki, Toshikatsu,Wang, Xiaowei,Ishihara, Kazuaki,Yamamoto, Hisashi
-
-
Read Online
- Solar and visible-light active nano Ni/g-C3N4photocatalyst for carbon monoxide (CO) and ligand-free carbonylation reactions
-
In this study, we investigate the amino and alkoxycarbonylation reaction between various substituted aryl halides, benzyl iodides, and iodocyclohexane with different types of amines and alcohols in the absence of carbon monoxide gas and ligands. Similar reactions are carried out at high temperatures, in the presence of appropriate ligands, stoichiometric amounts of bases, and gaseous carbon monoxide, which endanger the health of organic chemists. We present a novel method that does not utilize ligands, bases, gaseous CO, and special conditions. This procedure is a redox reaction carried out by new economic nano Ni/g-C3N4at room temperature and under visible light. Mo(CO)6was used toin situgenerate CO, to resolve the problems caused by the use of CO gas. This protocol has the ability to be used on a gram scale by using a continuous flow reactor.
- Hosseini-Sarvari, Mona,Akrami, Zahra
-
p. 956 - 969
(2021/02/26)
-
- Epoxide as precatalyst for metal-free catalytic transesterification
-
Transesterification of methyl esters was accelerated by an in situ-generated metal-free catalyst comprising a quaternary alkylammonium salt and an epoxide. The combination of a quaternary alkylammonium acetate and glycidol is optimal, and various esters were synthesized from methyl esters with alcohols in good to excellent yield. Analysis of the catalyst solution revealed that basic species are generated by the ring-opening reaction of epoxide.
- Tanaka, Shinji,Nakashima, Takuya,Satou,Oono, Hiromi,Kon, Yoshihiro,Tamura, Masanori,Sato, Kazuhiko
-
p. 2009 - 2013
(2019/07/03)
-
- Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
-
A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
- Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
-
p. 8083 - 8092
(2019/08/26)
-
- Aldehydes as potential acylating reagents for oxidative esterification by inorganic ligand-supported iron catalysis
-
The oxidative esterification of various aldehydes with alcohols could be achieved by a heterogeneous iron(iii) catalyst supported on a ring-like POM inorganic ligand under mild conditions, affording the corresponding esters, including several drug molecules and natural products, in high yields. ESI-MS and control experiments demonstrated that POM-FeV(O) was the active catalytic species and the plausible mechanism was presented. More importantly, the 6th run of the iron catalyst recycles shows only a slight decrease in the yield.
- Yu, Han,Wang, Jingjing,Wu, Zhikang,Zhao, Qixin,Dan, Demin,Han, Sheng,Tang, Jiangjiang,Wei, Yongge
-
supporting information
p. 4550 - 4554
(2019/08/21)
-
- Chelation-Based Homologation by Reaction of Organometallic Reagents with O -Alkyl S -Pyridin-2-yl Thiocarbonates: Synthesis of Esters from Grignard Reagents
-
The one-carbon homologative esterification of Grignard reagents with O- alkyl S -pyridin-2-yl thiocarbonates has been explored. This one-step synthesis of esters from Grignard reagents is the first case to involve chelation-stabilized intermediates.
- Hashimoto, Yoshimitsu,Mano, Koudai,Morita, Nobuyoshi,Suzuki, Tomoyuki,Tamura, Osamu,Tanaka, Kosaku,Usami, Shun
-
supporting information
p. 1561 - 1564
(2019/08/07)
-
- Sterically congested ester formation from α-substituted malononitrile and alcohol by an oxidative method using molecular oxygen
-
A metal-free oxidative esterification or thio-esterifica-tion of readily available substituted malononitrile and alcohol or thiol has been developed by simply mixing α-substituted malononitrile and alcohol or thiol in the presence of base under a molecular oxygen atmosphere. Sterically hindered ester or thioester can be prepared efficiently.
- Hayashi, Yujiro,Li, Jing,Asano, Hirotaka,Sakamoto, Daisuke
-
supporting information
p. 675 - 677
(2018/11/23)
-
- 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)
-
- Alkoxycarbonylation of olefins with carbon dioxide by a reusable heterobimetallic ruthenium-cobalt catalytic system
-
The heterobimetallic ruthenium-cobalt catalytic system exhibited good catalytic performance and reusability in the reductive alkoxycarbonylation of olefins with carbon dioxide. Compared to the previous system only consisting of ruthenium catalyst, the binary catalyst system effectively reduced the usage of noble metal and ionic liquid additives. The respective contribution of ruthenium and cobalt catalysts in this multiple-step catalytic process was investigated by a series of condition-controlled experiments. The evolution of the ruthenium catalyst and the occurrence of alkene hydrogenation during the reaction was explained by theortical calculations.
- Zhang, Xuehua,Shen, Chaoren,Xia, Chungu,Tian, Xinxin,He, Lin
-
p. 5533 - 5539
(2019/01/03)
-
- Zn-Catalyzed tert-Butyl Nicotinate-Directed Amide Cleavage as a Biomimic of Metallo-Exopeptidase Activity
-
A two-step catalytic amide-to-ester transformation of primary amides under mild reaction conditions has been developed. A tert-butyl nicotinate (tBu nic) directing group is easily introduced onto primary amides via Pd-catalyzed amidation with tert-butyl 2-chloronicotinate. A weak base (Cs2CO3 or K2CO3) at 40-50 °C can be used provided that 1,1′-bis(dicyclohexylphosphino)ferrocene is selected as ligand. The tBu nic activated amides subsequently allow Zn(OAc)2-catalyzed nonsolvolytic alcoholysis in tBuOAc at 40-60 °C under neutral reaction conditions. The activation mechanism is biomimetic: the C3-ester substituent of the pyridine in the directing group populates the trans-conformer suitable for Zn-chelation, C=Oamide-Zn-Ndirecting group, and Zn-coordinated alcohol is additionally activated as a nucleophile by hydrogen bonding with the acetate ligand of the catalyst. Additionally, the acetate ligand assists in intramolecular O-to-N proton transfer. The chemoselectivity versus other functional groups and compatibility with challenging reaction partners, such as peptides, sugars, and sterols, illustrates the synthetic applicability of this two-step amide cleavage method. The tBu nic amides do not require purification before cleavage. Preliminary experiments also indicate that other weak nucleophiles can be used such as (hetero)arylamines (transamidation) as exemplified by 8-aminoquinoline.
- Wybon, Clarence C. D.,Mensch, Carl,Hollanders, Charlie,Gadais, Charlène,Herrebout, Wouter A.,Ballet, Steven,Maes, Bert U. W.
-
p. 203 - 218
(2018/01/17)
-
- Synthesis, characterization and catalytic performances of benzimidazolin-2-iminato actinide (IV) complexes in the Tishchenko reactions for symmetrical and unsymmetrical esters
-
A new family of benzimdazolin-2-iminato actinide?(IV) complexes [(Bim7-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (3), Th (4)) and [(Bim4-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (5), Th (6)) were synthesized and their solid state structures were established by single-crystal X-ray diffraction analysis. The catalytic performances of complexes 3–6 towards the homo- and cross-coupling of aldehydes (Tishchenko reaction) were studied and the thorium complexes 4 and 6 displayed moderate to high activities for the production of the corresponding symmetric and unsymmetrical esters. Coupling of aldehyde and alcohols, known as the tandem proton-transfer esterification, and the intermolecular coupling reaction between aldehyde and trifluoromethylketones were also investigated by these thorium complexes, indicating a complementary method to obtain unsymmetrical esters selectively. Plausible mechanisms for these reactions are proposed based on stoichiometric studies.
- Liu, Heng,Khononov, Maxim,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
-
p. 123 - 137
(2017/10/25)
-
- Metal-free radical oxidative alkoxycarbonylation and imidation of alkanes
-
A metal-free radical oxidative carbonylation of alkanes is demonstrated, yielding esters and imides by means of di-tert-butylperoxide as an oxidant. Various alkanes, alcohols and amides were compatible in this system generating the desired carbonyl products in up to 86% yields. We proposed a plausible radical cross-coupling process based on the preliminary mechanistic studies.
- Lu, Lijun,Cheng, Danyang,Zhan, Yuanfeng,Shi, Renyi,Chiang, Chien-Wei,Lei, Aiwen
-
supporting information
p. 6852 - 6855
(2017/07/10)
-
- Copper-Catalyzed Alkoxycarbonylation of Alkanes with Alcohols
-
Esters are important chemicals widely used in various areas, and alkoxycarbonylation represents one of the most powerful tools for their synthesis. In this communication, a new copper-catalyzed carbonylative procedure for the synthesis of aliphatic esters from cycloalkanes and alcohols was developed. Through direct activation of the C sp3 ?H bond of alkanes and with alcohols as the nucleophiles, the desired esters were prepared in moderate-to-good yields. Paraformaldehyde could also be applied for in situ alcohol generation by radical trapping, and moderate yields of the corresponding esters could be produced. Notably, this is the first report on copper-catalyzed alkoxycarbonylation of alkanes.
- Li, Yahui,Wang, Changsheng,Zhu, Fengxiang,Wang, Zechao,Dixneuf, Pierre H.,Wu, Xiao-Feng
-
p. 1341 - 1345
(2017/04/14)
-
- Thorium complexes possessing expanded ring N-heterocyclic iminato ligands: Synthesis and applications
-
Six and seven membered N-heterocyclic iminato ligands (L) are introduced allowing access a new class of Th(iv) complexes of the type Cp?2Th(L)(CH3). These complexes were studied in the Tishchenko reaction. Stoichiometric reactions together with kinetic and thermodynamic studies permit us to propose a plausible mechanism.
- Ghatak, Tapas,Drucker, Shani,Fridman, Natalia,Eisen, Moris S.
-
supporting information
p. 12005 - 12009
(2017/09/25)
-
- Mitsunobu Reaction Using Basic Amines as Pronucleophiles
-
A novel protocol for extending the scope of the Mitsunobu reaction to include amine nucleophiles to form C-N bonds through the utilization of N-heterocyclic phosphine-butane (NHP-butane) has been developed. Both aliphatic alcohols and benzyl alcohols are suitable substrates for C-N bond construction. Various acidic nucleophiles such as benzoic acids, phenols, thiophenol, and secondary sulfonamide also provide the desired products of esters, ethers, thioether, and tertiary sulfonamide with 43-93% yields. Importantly, C-N bond-containing pharmaceuticals, Piribedil and Cinnarizine, have been synthesized in one step from the commercial amines under this Mitsunobu reaction system.
- Huang, Hai,Kang, Jun Yong
-
p. 6604 - 6614
(2017/07/15)
-
- Additive-Free Cobalt-Catalyzed Hydrogenation of Esters to Alcohols
-
Here, we report an additive-free catalytic system for hydrogenation of carboxylic acid esters to alcohols with a well-defined cobalt pincer catalyst precursor. Various substrates, including methyl, ethyl, and benzyl esters, have been evaluated under hydrogenation conditions; however, methyl esters have low reactivity compared to those of the corresponding ethyl and benzyl esters. The biomass-derived γ-valerolactone successfully formed 1,4-pentanediol with a turnover number of 3890 with this system. Metal-ligand cooperativity is probed with the related [PN(Me)P] derivative of the cobalt catalyst, and the results suggest a nonbifunctional hydrogenation mechanism.
- Yuwen, Jing,Chakraborty, Sumit,Brennessel, William W.,Jones, William D.
-
p. 3735 - 3740
(2017/06/09)
-
- Oxidation-Reduction Condensation of Diazaphosphites for Carbon-Heteroatom Bond Formation Based on Mitsunobu Mechanism
-
An efficient oxidation-reduction condensation reaction of diazaphosphites with various nonacidic pronucleophiles in the presence of DIAD as a weak oxidant has been developed for carbon-heteroatom bond formation. This mild process affords structurally diverse tertiary amines, secondary amines, esters, ethers, and thioethers in moderate to excellent yields. The selective synthesis of secondary amines from primary amines has been achieved. Importantly, a practical application to the synthesis of antiparkinsonian agent piribedil has been demonstrated.
- Huang, Hai,Kang, Jun Yong
-
supporting information
p. 544 - 547
(2017/02/10)
-
- Esterification of the Primary Benzylic C-H Bonds with Carboxylic Acids Catalyzed by Ionic Iron(III) Complexes Containing an Imidazolinium Cation
-
The first iron-catalyzed esterification of the primary benzylic C-H bonds with carboxylic acids using di-tert-butyl peroxide as an oxidant is achieved by novel ionic iron(III) complexes containing an imidazolinium cation. The use of well-defined, air-stable, and available iron(III) complex in a 5 mol % loading and readily available starting materials with a broad generality and outstanding sterically hindered tolerance renders this methodology a useful alternative to other protocols that are typically employed for the synthesis of benzyl esters.
- Lu, Bing,Zhu, Fan,Sun, Hong-Mei,Shen, Qi
-
supporting information
p. 1132 - 1135
(2017/03/14)
-
- Oxidative Alkane C?H Alkoxycarbonylation
-
Directly utilizing a chemical feedstock to construct valuable compounds is an attractive prospect in organic synthesis. In particular, the combination of C(sp3)?H activation and oxidative carbonylation involving alkanes and CO gas is a promising and efficient method to synthesize carbonyl derivatives. However, due to the high C?H bond dissociation energy and low polarity of unactivated alkanes, the carbonylation of unactivated C(sp3)?H bonds still remains a great challenge. In this work, we introduce a palladium-catalyzed radical oxidative alkoxycarbonylation of alkanes to prepare numerous alkyl carboxylates. Various alkanes and alcohols were compatible, generating the desired products in up to 94 % yield. Remarkably, ethane, a constituent of natural gas, could be employed as a substrate under the standard reaction conditions. Preliminary mechanistic studies revealed a probable palladium-catalyzed radical process.
- Lu, Lijun,Shi, Renyi,Liu, Luyao,Yan, Jingwen,Lu, Fangling,Lei, Aiwen
-
supporting information
p. 14484 - 14488
(2016/10/03)
-
- Cycloalkyl carboxylic acid ester compound preparation method
-
The present invention discloses a cycloalkyl formate compound preparation method, wherein in the presence of a palladium salt and a peroxide, a cycloalkane compound and an alcohol compound are dissolved in an organic solvent, the system is replaced by a carbon monoxide atmosphere, a reaction is performed for 16-24 h at a reaction temperature of 90-120 DEG C, and separation and purification are performed to obtain the cycloalkyl formate compound. According to the present invention, the used reactants are cheap and easy to obtain, the reaction conditions are simple, the atom economy is high, and the high-selectivity oxidation carbonylation reaction of the cycloalkane compound and the alcohol compound can be achieved so as to obtain the cycloalkyl formate compound; with the method, the precursor of the widely-used drug dicyclomine having treatment effects on intestines and stomach cramps and irritable bowel syndrome can be simply prepared; and the method has application potential in synthesis of drugs, natural products and the like.
- -
-
Paragraph 0017; 0018; 0019; 0020; 0021; 0022-0024; 0053
(2019/02/04)
-
- Mild Amide-Cleavage Reaction Mediated by Electrophilic Benzylation
-
An extremely mild method for amide-cleavage by using the triazine-based benzylating reagent 4-(4,6-diphenoxy-1,3,5-triazin-2-yl)-4-benzylmorpholinium trifluoromethanesulfonate (DPT-BM), which spontaneously releases benzyl cation species when being dissolved at room temperature, has been developed. O-Benzylation of the amide with DPT-BM and the subsequent hydrolysis of the resulting intermediate benzyl imidate salt afford the corresponding amine and benzyl ester, which can be converted by hydrogenolysis into a carboxylic acid under neutral conditions. O-Benzylation proceeds depending on both steric and electronic factors around the amide group. Thus, some amides have been selectively cleaved over other amides. Furthermore, intramolecular chemoselective cleavage of an amide group in the presence of an ester group was achieved. Such selective hydrolytic reactions cannot be performed with Meerwein reagents as well as under acidic or basic hydrolytic conditions.
- Yamada, Kohei,Karuo, Yukiko,Tsukada, Yuichi,Kunishima, Munetaka
-
p. 14042 - 14047
(2016/09/21)
-
- Synthesis of esters by in situ formation and trapping of diazoalkanes
-
A general method has been developed for the in situ formation and trapping of diazoalkanes by carboxylic acids to form esters. The method is applicable to a large variety of carboxylic acids using diazo compounds that are formed from the hydrazones of benzaldehydes and aryl ketones. In situ reaction monitoring with IR spectroscopy (ReactIR) was used to demonstrate that slow addition of the hydrazone to a mixture of oxidant and carboxylic acid avoids the buildup of the diazo compound. This method enables the safe preparation of esters from simple precursors without isolation of diazo compounds.
- Squitieri, Richard A.,Shearn-Nance, Galen P.,Hein, Jason E.,Shaw, Jared T.
-
p. 5278 - 5284
(2016/07/14)
-
- Mixed Imidazolin-2-iminato-Cp? Thorium(IV) Complexes: Synthesis and Reactivity Toward Oxygen-Containing Substrates
-
The mixed pentamethylcyclopentadienyl thorium(IV) imidazolin-2-iminato complexes Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) were synthesized in quantitative yields via rapid protonolysis of Cp?2Th(Me)2 (1) with the respective neutral imidazolin-2-iminato ligand ImRNH. Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) display short Th-N bond lengths and large Th-N-C angles. The reactivity of complex 2 and 3 toward oxygen-containing substrates was studied, and the catalytic activity of 2 was compared to the dimethyl (bispentamethyl-cyclopentadienyl) thorium complex 1. Complex 2 was applied in the catalytic Tishchenko reaction with aromatic, heteroaromatic, and branched aliphatic aldehydes, displaying a higher catalytic activity than Cp?2Th(Me)2 and Cp?2Th(ImMesN)(Me). Furthermore, 2 was applied as a catalyst in the crossed Tishchenko reaction and in the oligomerization of bis(aldehydes), as well as in the ring-opening polymerization of ε-caprolactone. In all reactions, the activity of Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) was higher than that observed for Cp?2Th(Me)2 (1), which can be attributed to the increased electron density introduced by the coordination of the imidazolin-2-iminato ligand. (Chemical Equation Presented).
- Karmel, Isabell S. R.,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
-
supporting information
p. 2933 - 2942
(2015/06/30)
-
- Ester manufacturing method (by machine translation)
-
PROBLEM TO BE SOLVED: To produce an ester compound by transesterification using an inexpensive and low toxic inorganic compound. SOLUTION: Transesterification of an ester compound and an alcohol compound is carried out under the presence of lanthanum nitrate (for example, lanthanum nitrate hexahydrate) and a phosphine compound (for example, tri-n-octylphosphine), thereby obtaining the ester product. For example, transesterification of dimethyl carbonate and benzyl alcohol is carried out under the presence of 1 mol% of lanthanum nitrate hexahydrate, and 2 mol% of tri-n-octylphosphine, thereby obtaining benzyl methylcarbonate at a yield of >99%. COPYRIGHT: (C)2012,JPO&INPIT
- -
-
Paragraph 0054; 0055; 0056
(2017/02/17)
-
- O-Benzylation of Carboxylic Acids Using 2,4,6-Tris(benzyloxy)-1,3,5-triazine (TriBOT) under Acidic or Thermal Conditions
-
Two methods for the synthesis of benzyl esters from carboxylic acids using the O-benzylating reagent 2,4,6-tris(benzyloxy)-1,3,5-triazine (TriBOT) have been developed. The reactions were conducted either in the presence of a catalytic amount of TfOH at room temperature (acidic conditions) or in the absence of TfOH at 180-230 C (thermal conditions). Interestingly, the O-benzylation of hydroxy carboxylic acids under the two conditions afforded different products: The dibenzylated product under acidic conditions and the hydroxy ester under thermal conditions. In addition to these results, other evidence indicated that the former reaction proceeds through an SN1-type mechanism, and the latter by an SN2-type mechanism. Two methods for the O-benzylation of carboxylic acids using TriBOT have been developed under either acidic or thermal conditions. The O-benzylation of hydroxy carboxylic acids afforded the dibenzylated product under acidic conditions and the hydroxy ester under thermal conditions. The former reaction proceeds through an SN1-type mechanism and the latter by an SN2-type mechanism.
- Yamada, Kohei,Yoshida, Saki,Fujita, Hikaru,Kitamura, Masanori,Kunishima, Munetaka
-
p. 7997 - 8002
(2015/12/24)
-
- Magnesium-catalyzed hydroboration of esters: Evidence for a new zwitterionic mechanism
-
A magnesium-catalyzed ester hydroboration reaction rapidly and efficiently (a pathway involving a zwitterionic alkoxyborate is proposed. The Royal Society of Chemistry 2014.
- Mukherjee, Debabrata,Ellern, Arkady,Sadow, Aaron D.
-
p. 959 - 964
(2014/03/21)
-
- Hydroesterification of alkenes with sodium formate and alcohols promoted by cooperative catalysis of Ru3(CO)12 and 2-pyridinemethanol
-
(Figure Presented) A chelation-assisted hydroesterification reaction of alkenes with sodium formate and alcohols that involves cooperative catalysis by Ru3(CO)12 and 2-pyridinemethanol is described. In this three-component coupling reaction, sodium formate serves as the carbon monoxide source.
- Kim, Dong-Su,Park, Woo-Jin,Lee, Chang-Hee,Jun, Chul-Ho
-
p. 12191 - 12196
(2015/01/09)
-
- Novel ruthenium-catalyst for hydroesterification of olefins with formates
-
An alternative ruthenium-based catalyst for the hydroesterification of olefins with formates is reported. The good activity of our system is ensured by the use of a bidentate P,N-ligand and ruthenium dodecacarbonyl. A range of formates can be used for selective alkoxycarbonylation of aromatic olefins. In addition, the synthesis of selected aliphatic esters is realized. The proposed active ruthenium complex has been isolated and characterized. This journal is the Partner Organisations 2014.
- Profir, Irina,Beller, Matthias,Fleischer, Ivana
-
supporting information
p. 6972 - 6976
(2014/10/15)
-
- Phosphorus oxychloride as an efficient coupling reagent for the synthesis of esters, amides and peptides under mild conditions
-
A mild method is described for the conversion of carboxylic acids into esters, amides, as well as peptides without racemization through carboxyl activation by the reagent combination of POCl3 and DMAP. Long chain alcohols could be converted to the corresponding ester in good yields. 31P NMR spectrum was used to detect phosphorus-containing intermediates in ongoing reactions directly, and a possible mechanism has been proposed based on these results. The Royal Society of Chemistry 2013.
- Chen, Hu,Xu, Xunfu,Liu, Liu,Tang, Guo,Zhao, Yufen
-
p. 16247 - 16250
(2013/09/23)
-
- Palladium-catalyzed benzylation of carboxylic acids with toluene via benzylic C-H activation
-
Direct benzylation of carboxylic acids with toluene has been developed via palladium-catalyzed C-H acyloxylation under 1 atm of oxygen. This reaction demonstrates good functional group tolerance and high yields, providing a facile, atom-economic, and efficient method for the synthesis of benzyl esters.
- Liu, Hongqiang,Shi, Guangfa,Pan, Shulei,Jiang, Yuyu,Zhang, Yanghui
-
supporting information
p. 4098 - 4101
(2013/09/12)
-
- Aniline mediated oxidative C-C bond cleavage of α-alkoxy aldehydes in air and a model reaction for the synthesis of α-(d)-amino acid derivatives
-
A metal-free and 4-methyl aniline mediated method for the oxidative C-C bond cleavage has been developed. The reaction proceeds in air using molecular oxygen as the oxidant, affording one-carbon shortened esters in moderate to good yields within a short time. Moreover, it provides a model reaction for the highly enantioselective synthesis of (d)-serine esters by combining with a l-proline catalyzed Mannich reaction.
- Hu, Bin,Li, Yunfeng,Li, Zhongjun,Meng, Xiangbao
-
supporting information
p. 4138 - 4141
(2013/07/05)
-
- Cooperative N-Heterocyclic Carbene (NHC) and Ruthenium Redox Catalysis: Oxidative Esterification of Aldehydes with Air as the Terminal Oxidant
-
The paper describes a cooperative NHC (N-heterocyclic carbene) and ruthenium-based redox catalysis for the mild aerobic oxidative esterification of various aromatic and heteroaromatic aldehydes. The ruthenium(II) complex Ru(bpz)3(PF6)2 (bpz=2,2′-bipyrazine) as catalyst is shown to be compatible with free NHCs. The NHC is used in these cascade reactions for the umpolung of the aldehyde to form the corresponding Breslow intermediate which in turn gets oxidized to an acylazolium ion by the ruthenium redox catalyst. Air is used as a terminal oxidant for oxidation (regeneration) of the ruthenium catalyst. In addition, we will show that in the absence of the ruthenium redox catalyst and alcohol, NHC-catalyzed aerobic oxidation of aldehydes delivers the corresponding acids in good to excellent yields. Mechanistic studies and DFT calculations supporting our suggested mechanisms are provided. Copyright
- Zhao, Junfeng,Mueck-Lichtenfeld, Christian,Studer, Armido
-
supporting information
p. 1098 - 1106
(2013/05/21)
-
- Organocatalyzed anodic oxidation of aldehydes
-
A method for the catalytic formation of electroauxiliaries and subsequent anodic oxidation has been developed. The process interfaces N-heterocyclic carbene-based organocatalysis with electro-organic synthesis to achieve direct oxidation of catalytically generated electroactive intermediates. We demonstrate the applicability of this method as a one-pot conversion of aldehydes to esters for a broad range of aldehyde and alcohol substrates. Furthermore, the anodic oxidation reactions are very clean, producing only H2 gas as a result of cathodic reduction.
- Finney, Eric E.,Ogawa, Kelli A.,Boydston, Andrew J.
-
supporting information; experimental part
p. 12374 - 12377
(2012/09/05)
-
- Use of diethoxymethane as a solvent for phase-transfer esterification of carboxylic acids
-
The esterification of carboxylic acids with selected primary alkyl halides in diethoxymethane (DEM) utilizing solid-liquid phase-transfer catalysis has been studied. The use of DEM as the solvent simplifies the process in that a single solvent can be used for both reaction and workup.
- Coleman, M. Todd
-
scheme or table
p. 1911 - 1913
(2012/06/04)
-
- Oxidation of primary aliphatic and aromatic aldehydes with difluoro(aryl)-λ3-bromane
-
Oxidation of primary aliphatic aldehydes with p- trifluoromethylphenyl(difluoro)-λ3-bromane in dichloromethane at 0 °C afforded acid fluorides selectively in good yields, while that of aromatic aldehydes in chloroform at room temperature produced aryl difluoromethyl ethers. A larger migratory aptitude of aryl groups compared to primary alkyl groups during a 1,2-shift from carbon to an electron-deficient oxygen atom in bromane(III) Criegee-type intermediates will result in these differences in the reaction courses.
- Ochiai, Masahito,Yoshimura, Akira,Hoque, Md. Mahbubul,Okubo, Takuji,Saito, Motomichi,Miyamoto, Kazunori
-
p. 5568 - 5571
(2011/12/03)
-
- Nickel-catalyzed selective conversion of two different aldehydes to cross-coupled esters
-
In the presence of a Ni(0)/NHC catalyst, an equimolar mixture of aliphatic and aryl aldehydes can be employed to selectively yield a single cross-coupled ester. This reaction can be applied to a variety of aliphatic (1°, 2°, cyc-2°, and 3°) and aryl aldehyde combinations. The reaction represents 100% atom efficiency and generates no waste. Mechanistic studies have revealed that the striking feature of the reaction is the simultaneous coordination of two aldehydes to Ni(0).
- Hoshimoto, Yoichi,Ohashi, Masato,Ogoshi, Sensuke
-
supporting information; experimental part
p. 4668 - 4671
(2011/05/16)
-
- Zwitterionic salts as mild organocatalysts for transesterification
-
(Chemical Equation Presented) The exothermic reaction of 3,5-bis(trifluoromethyl)phenyl or 4-nitrophenyl isothiocyanate with 4-pyrrolidinopyridine (PPY) gave the corresponding arylaminothiocarbonylpyridinium salts in quantitative yields. These novel zwitterionic salts were effective as organocatalysts for the transesterification reaction of an equimolar mixture of methyl carboxylates and alcohols in hydrocarbons such as heptane and octane under azeotropic reflux conditions with the removal of methanol. In sharp contrast, PPY was inert as a catalyst under the same reaction conditions.
- Ishihara, Kazuaki,Niwa, Masatoshi,Kosugi, Yuji
-
supporting information; experimental part
p. 2187 - 2190
(2009/05/27)
-
- Cyclopropanecarboxylic acid esters as potential prodrugs with enhanced hydrolytic stability
-
Esters of cyclopropanecarboxylic acid demonstrate a substantial increase in stability under both acid- and base-catalyzed hydrolytic conditions. Comparison of the stability of valacyclovir 13 with the cyclopropane analogue 14 shows that at 40 °C and pH 6 the half-life of 14 is >300 h while the value for 13 is 69.7 h. CBS-QB3 calculations on isodesmic reactions for transfer of groups from an alkane to an ester show that a cyclopropyl group provides hyperconjugative stabilization.
- Bender, David M.,Peterson, Jeffrey A.,McCarthy, James R.,Gunaydin, Hakan,Takano, Yu,Houk
-
p. 509 - 511
(2008/09/19)
-
- Development of fluorous lewis acid-catalyzed reactions
-
Organic synthetic methodology in the 21st century aims to conform to the principles of green sustainable chemistry (GSC) and we may expect that in the future, the realization of GSC will be an important objective for chemical industries. An important aim of synthetic organic chemistry is to implement waste-free and environmentally-benign industrial processes using Lewis acids as versatile as aluminum choride. A key technological objective of our work in this area has been to achieve a "catalyst recycling system that utilizes the high activity and structural features of fluorous Lewis acid catalysts". Thus, we have developed a series of novel fluorous Lewis acid catalysts, namely the ytterbium(III), scandium(III), tin(IV) or hafnium(IV) bis(perfluoroalkanesulfonyl)amides or tris(perfluoro- alkanesulfonyl)methides. Our catalysts are recyclable and effective for acylations of alcohols and aromatics, Baeyer-Villiger reactions, direct esterifications and transesterifications in a fluorous biphasic system (FBS), in supercritical carbon dioxide and on fluorous silica gel supports.
- Yoshida, Akihiro,Hao, Xiuhua,Yamazaki, Osamu,Nishikido, Joji
-
p. 627 - 640
(2007/10/03)
-
- Metal bis(perfluorooctanesulfonyl)amides as highly efficient Lewis acid catalysts for fluorous biphase organic reactions
-
In fluorous biphase system, metal bis(perfluorooctanesulfonyl)amides are better Lewis acid catalysts than the analogous triflates toward either transesterifications, or direct esterifications, or Friedel-Crafts acylations or Baeyer-Villiger oxidations. These catalysts are selectively soluble in lower fluorous phase and can be recovered simply by phase separation. Furthermore, these catalysts can be reused without decrease of activity in most cases.
- Hao, Xiuhua,Yoshida, Akihiro,Nishikido, Joji
-
p. 193 - 199
(2007/10/03)
-
- ZrOCl2·8H2O: An efficient, cheap and reusable catalyst for the esterification of acrylic acid and other carboxylic acids with equimolar amounts of alcohols
-
Esterifications of carboxylic acids with equimolar amount of alcohols could be efficiently catalyzed by ZrOCl2·8H2O. Acrylate esters were obtained in good yields under solvent-free conditions at ambient temperature. The esterification of other carboxylic acids with alcohols also proceeded at ambient temperature or at 50°C to afford esters in high yields. If the esterification was performed in toluene under azeotropic reflux conditions to remove water, both the catalytic activity of ZrOCl 2·8H2O and the rate of esterification could be increased greatly. Furthermore, in the present catalytic system, the esters could be easily separated from the reaction mixtures and the catalyst could be easily recovered and reused.
- Sun, Hong-Bin,Hua, Ruimao,Yin, Yingwu
-
p. 263 - 271
(2007/10/03)
-
- NOVEL 4-(2FUROYL)AMINOPIPERIDINES, INTERMEDIATES IN SYNTHESIZING THE SAME,PROCESS FOR PRODUCING THE SAME AND MEDICINAL USE OF THE SAME
-
There are provided novel 4-(2-furoyl)aminopiperidines represented by the general formula (I), their synthetic intermediates, processes for their preparation and medicaments containing them. In the above formula, X is CH or N, and Y is a group of the following general formula (II), formula (II-a) or formula (III): wherein a, b and c are each an integer of 0-6; Z is CH2 or NH; W is O or S; T is O or N-R15 wherein R15 is H, a C1-C6 alkyl group, a benzyl group or a phenethyl group; and R1 is H, a C1-C6 alkoxycarbonyl group, a benzyloxycarbonyl group, or the like.The 4-(2-furoyl) aminopiperidine derivatives according to this invention possess opioid μ antagonistic activity and are useful for the treatment or prevention of side effects which are caused by μ receptors agonist and which are selected from constipation, nausea/emesis or itch, or for the treatment or prevention of idiopathic constipation, postoperative ileus, paralytic ileus, irritable bowel syndrome or chronic pruritus.
- -
-
-
- Conversion of α-haloaldehydes into acylating agents by an internal redox reaction catalyzed by nucleophilic carbenes
-
Reactivity umpolung allows us to consider nontraditional bond disconnections. We report herein that treatment of an α-haloaldehyde with a nucleophile in the presence of catalytic amounts of nucleophilic carbenes results in an internal redox reaction giving rise to a dehalogenated acylating agent as an intermediate by a new reaction manifold. A brief illustration of the scope of this reaction is presented along with evidence supporting the direct intervention of the carbene in the acylation step. Copyright
- Reynolds, Nathan T.,De Alaniz, Javier Read,Rovis, Tomislav
-
p. 9518 - 9519
(2007/10/03)
-
- Process for producing esterificated condensate
-
The present invention provides a method for preparing ester or thioester that can conduct catalytic esterification reaction with an equimolar amount of carboxylic acid and alcohol, or catalytic thioesterification reaction with carboxylic acid and an equimolar amount or small amount of thiol, and can be expected as an industrial method that needs an enormous amount of synthesis in the light of green chemistry. By using hafnium chloride (IV), especially tetravalent hafnium compounds represented by hafnium chloride (IV)?(THF)2 or hafnium (IV)t-butoxide as a (poly) condensation catalyst, direct condensation reaction is conducted from carboxylic acid and an equimolar amount of alcohol or a little smaller amount of thiol, in the nonpolar solvent such as toluene and the like, in a deoxidization atmosphere and under heating reflux, and the reaction synthesizes ester monomer or thioester monomer, polyester or polythioester. When heating reflux is conducted by using a nonpolar solvent, it is preferable to remove azeotropic water from the reaction system.
- -
-
-
- Recyclable and selective Lewis acid catalysts for transesterification and direct esterification in a fluorous biphase system: Tin(IV) and hafnium(IV) bis(perfluorooctanesulfonyl)amide complexes
-
Tin(IV) and hafnium(IV) bis(perfluorooctanesulfonyl)amide complexes were shown to give excellent yield and selectivity for highly practical transesterification and direct esterification, respectively, with an equimolar ratio of the reactants in a fluorous biphase system. It was found that these metal complexes were completely recovered and reused in the immobilized fluorous phase without loss of their catalytic activities.
- Hao, Xiuhua,Yoshida, Akihiro,Nishikido, Joji
-
p. 781 - 785
(2007/10/03)
-
- Lewis Acids as Highly Efficient Catalysts for the Decarboxylative Esterification of Carboxylic Acids with Dialkyl Dicarbonates
-
Mild Lewis acids such as Mg(ClO4)2 show a new level of catalytic activity for the decarboxylative esterification of carboxylic acids with commercially available dialkyl dicarbonates. In the presence of as little as one mol % Mg(ClO4)2 catalyst, carboxylic acids can thus easily and near quantitatively be protected at room temperature, e.g., as methyl, benzyl, or t-butyl esters. Only volatile by-products are released so that the purification of the products is particularly easy. Many sensitive functionalities are tolerated, including even phenol esters, or free hydroxy and BOC groups.
- Goossen,Doehring
-
p. 943 - 947
(2007/10/03)
-
- Preparation of acyl fluorides with hydrogen fluoride-pyridine and 1,3-dicyclohexylcarbodiimide
-
This work presents an efficient procedure for preparing acyl fluorides by simply reacting carboxylic acid with hydrogen fluoride-pyridine and 1,3-dicyclohexylcarbodiimide (DCC) in dichloromethane. The acyl fluorides were converted in situ to the corresponding benzyl carboxylic esters by adding benzyl alcohol and triethylamine to the reaction mixture.
- Chen, Chinpiao,Chien, Chin-Tzu,Su, Chu-Hsiang
-
-
- Direct ester condensation from a 1:1 mixture of carboxylic acids and alcohols catalyzed by hafnium(IV) or zirconium(IV) salts
-
To promote atom efficiency in synthesis and to avoid the generation of environmental waste, the use of stoichiometric amounts of condensing reagents or excess substrates should be avoided. In esterification, excess amounts of either carboxylic acids or alcohols are normally needed. We found that the direct condensation of equimolar amounts of carboxylic acids and alcohols could be achieved using hafnium(IV) or zirconium(IV) salts. These metal salts are highly effective as catalysts for the selective esterification of primary alcohols with carboxylic acids in the presence of secondary alcohols or aromatic alcohols. The present methods can be applied to direct polyesterification and may be suitable for large-scale operations.
- Ishihara, Kazuaki,Nakayama, Masaya,Ohara, Suguru,Yamamoto, Hisashi
-
p. 8179 - 8188
(2007/10/03)
-
- Esterification of carboxylic acids catalyzed by in situ generated tetraalkylammonium fluorides
-
Esterification of carboxylic acids with alkyl halides can be efficiently catalyzed by tetrabutylammonium fluoride (TBAF) generated in situ from tetrabutylammonium hydrogensulfate (TBAHSO4) and KF·2H2O in THF. The general applicability and the characteristic feature of this approach has been amply demonstrated.
- Ooi, Takashi,Sugimoto, Hayato,Doda, Kanae,Maruoka, Keiji
-
p. 9245 - 9248
(2007/10/03)
-