- CH-π Interaction as an Important Driving Force of Host-Guest Complexation. Further Evidence for the Selective Incorporation of Alkyl Groups in the Polyhydroxy Aromatic Cavity of Calix[4]resorcarene Host
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The complexation of a calix[4]resorcarene host (2,8,14,20-tetraundecylcalix[4]arene-4,6,10,12,16,18,22,24-octol) with borneol in benzene or alkylbenzene was investigated by circular dichroism (CD) spectroscopy. The binding constants are dramatically solvent-dependent and decrease with respect to the substituents on the benzene ring in the order H>methyl>ethyl>propyl>butyl. The complexation of the same host with alkyl benzoates in limonene as a chiral hydrocarbon solvent was readily monitored by following their competitive inhibition effects on the CD intensities, reflecting the chiral host-solvent interaction. The binding constants for alkyl benzoates were again highly dependent on the alkyl groups, and changed in the order decylhexylmethylpropyl≈pentyl?butyl. There is thus an optimal chain length at butyl. These results provide further evidence for the selective incorporation of alkyl groups in the polyhydroxy aromatic cavity of the host.
- Kikuchi, Yasuaki,Aoyama, Yasuhiro
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Read Online
- Erratum: Ruthenium-catalyzed C-H hydroxylation in aqueous acid enables selective functionalization of amine derivatives (Journal of the American Chemical Society (2017) 139:28 (9503-9506) DOI: 10.1021/jacs.7b05469)
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Page 9504. The structure of product 3cc in Table 2 was found to be mis-assigned. We thank Prof. Phil Baran and Dr. Rafael Navratil for bringing this error to our attention. The correct structure contains an additional benzylic alcohol at the C-9 position of the steroid (3cc′, shown below). With the accompanying change in molecular weight, the isolated yield is 29%. Supporting Information. The incorrect structure and yield also appeared on pages S20 and S84 in the SI. Given this, the HRMS entry on page S20 should read as follows: “HRMS (ESI-TOF) m/z calcd for C19H18F3O5S+ (M-O+Na)+ 415.0822, found 415.0857”. The complete corrected SI is provided here.
- Mack, James B.C.,Gipson, John D.,Du Bois,Sigman, Matthew S.
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supporting information
p. 3016 - 3016
(2021/03/01)
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- N-Ammonium Ylide Mediators for Electrochemical C-H Oxidation
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The site-specific oxidation of strong C(sp3)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds to truncating retrosynthetic plans, there is a growing need for new reagents and methods for achieving such a transformation in both academic and industrial circles. One main drawback of current chemical reagents is the lack of diversity with regard to structure and reactivity that prevents a combinatorial approach for rapid screening to be employed. In that regard, directed evolution still holds the greatest promise for achieving complex C-H oxidations in a variety of complex settings. Herein we present a rationally designed platform that provides a step toward this challenge using N-ammonium ylides as electrochemically driven oxidants for site-specific, chemoselective C(sp3)-H oxidation. By taking a first-principles approach guided by computation, these new mediators were identified and rapidly expanded into a library using ubiquitous building blocks and trivial synthesis techniques. The ylide-based approach to C-H oxidation exhibits tunable selectivity that is often exclusive to this class of oxidants and can be applied to real-world problems in the agricultural and pharmaceutical sectors.
- Saito, Masato,Kawamata, Yu,Meanwell, Michael,Navratil, Rafael,Chiodi, Debora,Carlson, Ethan,Hu, Pengfei,Chen, Longrui,Udyavara, Sagar,Kingston, Cian,Tanwar, Mayank,Tyagi, Sameer,McKillican, Bruce P.,Gichinga, Moses G.,Schmidt, Michael A.,Eastgate, Martin D.,Lamberto, Massimiliano,He, Chi,Tang, Tianhua,Malapit, Christian A.,Sigman, Matthew S.,Minteer, Shelley D.,Neurock, Matthew,Baran, Phil S.
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supporting information
p. 7859 - 7867
(2021/05/26)
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- LiHMDS: Facile, highly efficient and metal-free transesterification under solvent-free condition
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Transesterification is one of the important organic reactions employed in numerous industrial as well as laboratory applications for the synthesis of various esters. Herein, we report a rapid, highly efficient, and transition metal-free transesterification reaction in the presence of LiHMDS under solvent-free conditions. The transesterification reaction was carried out with three different benzoate esters and a wide range of primary and secondary alcohols (from C3-C18) in good to excellent yields (45 examples). By considering the commercial role of esters, this method will be promising for the facile synthesis of esters in industry-relevant applications.
- Gore, Kiran R.,Mittapelli, Lavanya L.
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- Electrochemical esterification via oxidative coupling of aldehydes and alcohols
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An electrolytic method for the direct oxidative coupling of aldehydes with alcohols to produce esters is described. Our method involves anodic oxidation in presence of TBAF as supporting electrolyte in an undivided electrochemical cell equipped with graphite electrodes. This method successfully couples a wide range of alcohols to benzaldehydes with yields ranging from 70 to 90%. The protocol is easy to perform at a constant voltage conditions and offers a sustainable alternative over conventional methods.
- Smeyne, Dylan,Verboom, Katherine,Bryan, Maria,LoBue, James,Shaikh, Abid
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supporting information
(2021/03/26)
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- Macrolactonization Reactions Driven by a Pentafluorobenzoyl Group**
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Macrolactones constitute a privileged class of natural and synthetic products with a broad range of applications in the fine chemicals and pharmaceutical industry. Despite all the progress made towards their synthesis, notably from seco-acids, a macrolactonization promoter system that is effective, selective, flexible, readily available, and, insofar as possible, compatible with manifold functional groups is still lacking. Herein, we describe a strategy that relies on the formation of a mixed anhydride incorporating a pentafluorophenyl group which, due to its high electronic activation enables a convenient access to macrolactones, macrodiolides and esters with a broad versatility. Kinetic studies and DFT computations were performed to rationalize the reactivity of the pentafluorophenyl group in macrolactonization reactions.
- Ciofini, Ilaria,Force, Guillaume,Leb?uf, David,Mayer, Robert J.,Perfetto, Anna
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supporting information
p. 19843 - 19851
(2021/08/13)
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- Palladium-Catalyzed Para-Selective Difluoromethylation of Arene Esters
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Highly efficient, palladium-catalyzed, para-selective difluoromethylation of arene esters has been developed using [1,1′-biphenyl]-2-dicyclohexylphosphine as the effective ligand. A wide variety of arene esters bearing various functional groups were all compatible with the reaction conditions, leading to para-difluoromethylated products in moderate to good yields. Moreover, benzoylamide and benzenesulfonamide were also well-tolerated, suggesting that this novel catalyst system has broad applications to a variety of substrates.
- Tu, Guangliang,Wang, Dongjie,Yuan, Chunchen,Zhang, Jingyu,Zhao, Yingsheng
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p. 10740 - 10749
(2020/09/18)
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- Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
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The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
- Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
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supporting information
p. 8143 - 8146
(2020/09/09)
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- 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
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Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.
- Khosravi, Kaveh,Naserifar, Shirin
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p. 6584 - 6592
(2018/10/05)
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- Superior performance of Co-N/m-C for direct oxidation of alcohols to esters under air
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A convenient, expeditious, and high-efficiency protocol for the transformation of alcohols into esters using a Co-modified N-doped mesoporous carbon material (Co-N/m-C) as the catalyst is proposed. The catalyst was prepared through direct pyrolysis of a macromolecular precursor. The catalyst prepared using a pyrolysis temperature of 900 °C (labeled Co-N/m-C-900) exhibited the best performance. The strong coordination between the ultra-dispersed cobalt species and the pyridine nitrogen as well as the large area of the mesoporous surface resulted in a high turnover frequency value (107.6 mol methyl benzoate mol?1 Co h?1) for the direct aerobic oxidation of benzyl alcohol to methyl benzoate. This value is much higher than those of state-of-the-art transition-metal-based nanocatalysts reported in the literature. Moreover, the catalyst exhibited general applicability to various structurally diverse alcohols, including benzylic, allylic, and heterocyclic alcohols, achieving the target esters in high yields. In addition, a preliminary evaluation revealed that Co-N/m-C-900 can be used six times without significant activity loss. In general, the process was rapid, simple, and cost-effective.
- Li, Ning,Shang, Sensen,Wang, Lianyue,Niu, Jingyang,Lv, Ying,Gao, Shuang
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p. 1249 - 1257
(2018/06/14)
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- Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional sustainable catalysts for base-free selective oxidative esterification of alcohols
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We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM, HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was explored for base-free selective oxidative esterification of alcohols to the corresponding esters under mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were discerned. Furthermore, the substrate scope was explored for the cross-esterification of benzyl alcohol with long-chain alcohols (up to 98%) and lactonization of diols (up to 68%). The heterogeneous nature and stability of the catalyst facilitated by its ease of separation for long-term performance and recycling studies showed that the catalyst was robust and remained active even after six recycling experiments. EPR measurements were performed to deduce the reaction mechanism in the presence of POBN (α-(4-pyridyl-1-oxide)-N-tert-butylnitrone) as a spin-trapping agent, which confirmed the formation of CH2OH radicals and H radicals, wherein the solvent plays an active role in a nonconventional manner. A plausible mechanism was proposed for the oxidative esterification of alcohols on the basis of EPR findings. The presence of a cobalt core along with cobalt oxide and the electron-rich N-, O-, and S-doped carbon shell displayed synergistic effects to afford good to excellent yields of products.
- Nandan, Devaki,Zoppellaro, Giorgio,Med?ík, Ivo,Aparicio, Claudia,Kumar, Pawan,Petr, Martin,Tomanec, Ond?ej,Gawande, Manoj B.,Varma, Rajender S.,Zbo?il, Radek
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p. 3542 - 3556
(2018/08/07)
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- Preparation, structure, and reactivity of bicyclic benziodazole: A new hypervalent iodine heterocycle
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A new bicyclic organohypervalent iodine heterocycle derivative of benziodazole was prepared by oxidation of 2-iodo-N,N'-diiso-propylisophthalamide with m-chloroperoxybenzoic acid under mild conditions. Single crystal X-ray crystallography of this compound revealed a five-membered bis-heterocyclic structure with two covalent bonds between the iodine atom and the nitrogen atoms. This novel benziodazole is a very stable compound with good solubility in common organic solvents. This compound can be used as an efficient reagent for oxidatively assisted coupling of carboxylic acids with alcohols or amines to afford the corresponding esters or amides in moderate yields.
- Jarvi, Melissa E.,Makitalo, Cody L.,Rohde, Gregory T.,Saito, Akio,Shea, Michael T.,Yoshimura, Akira,Yusubov, Mekhman S.,Zhdankin, Viktor V.
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supporting information
p. 1016 - 1020
(2020/05/06)
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- Ruthenium-Catalyzed C-H Hydroxylation in Aqueous Acid Enables Selective Functionalization of Amine Derivatives
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The identification, optimization, and evaluation of a new catalytic protocol for sp3 C-H hydroxylation is described. Reactions are performed in aqueous acid using a bis(bipyridine)Ru catalyst to enable oxidation of substrates possessing basic amine functional groups. Tertiary and benzylic C-H hydroxylation is strongly favored over N-oxidation for numerous amine derivatives. With terpene-derived substrates, similar trends in reactivity toward tertiary and benzylic C-H bonds are observed. Hydroxylation of chiral tertiary centers is enantiospecific in spite of the ionizing strength of the reaction medium. Preliminary kinetics experiments show a marked difference in reactivity between isomeric cis- and trans-Ru catalysts suggesting that the catalyst is configurationally stable under the reaction conditions.
- Mack, James B. C.,Gipson, John D.,Du Bois,Sigman, Matthew S.
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supporting information
p. 9503 - 9506
(2017/07/24)
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- Highly Active Manganese-Mediated Acylation of Alcohols with Acid Chlorides or Anhydrides
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To explore further the practical uses of highly active manganese (Mn?), a variety of alcohols were treated with Mn?, and the resulting complexes were coupled with acid chlorides and/or acetic anhydride in the absence of any extra catalyst. The subsequent reactions took place smoothly under mild conditions, providing the corresponding O-acylation products in good to excellent isolated yields.
- Joo, Seong-Ryu,Youn, Young-Jin,Hwang, Young-Ran,Kim, Seung-Hoi
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p. 2665 - 2669
(2017/10/07)
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- H-Bonding-promoted radical addition of simple alcohols to unactivated alkenes
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H-Bonding-induced radical addition of simple alcohols to unactivated olefins was achieved. It effectively solved the long-standing problems of reactivity and selectivity in this type of reaction. The hydroxyalkylation occurred via site-specific cleavage of the α-hydroxyl-C-H bond in alcohols. This method allows a highly atom-economical, operationally simple and environmentally benign access to diverse primary, secondary and tertiary alcohols, diols, and even polyfluorinated alcohols. These useful chemicals are traditionally synthesized by using commercially unavailable organometallics via complex operations. In contrast, they can be facilely obtained through this protocol utilizing widely available starting materials.
- Tian, Yunfei,Liu, Zhong-Quan
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p. 5230 - 5235
(2017/11/09)
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- Acid promoted C-C bond oxidative cleavage of β-O-4 and β-1 lignin models to esters over a copper catalyst
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Depolymerisation of lignin to aromatics is a challenging task. We herein report that a Cu(OAc)2/BF3·OEt2 catalyst is effective in simultaneously cleaving C-C bonds in β-1 and β-O-4 ketones, yielding esters and phenols. In-depth studies show that C-H bond activation is the rate determining step for C-C bond cleavage. BF3·OEt2 promotes the reaction via activating the β-C-H bond. This study offers the potential to obtain aromatic esters from lignin.
- Wang,Li,Lu,Li,Zhang,Liu,Luo,Wang
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p. 702 - 706
(2017/08/15)
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- Solvent- and Metal-free Oxidative Esterification of Aromatic Aldehydes Using Urea-2,2-dihydroperoxypropane as a New Solid Oxidant
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Urea-2,2-dihydroperoxypropane as a noble and solid gem-dihydroperoxide derivative was used to transform various aromatic aldehydes to their corresponding benzoate derivatives in the presence of HBr under mild conditions at room temperature in high yields and short reaction times.
- Khosravi, Kaveh,Khalaji, Kobra,Naserifar, Shirin
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p. 303 - 309
(2017/03/27)
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- Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions
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A highly efficient palladium-catalyzed approach for the direct oxidative esterification of benzylic alcohols with methanol and long-chain aliphatic alcohols under mild conditions has been achieved. This practical catalyst system exhibits a broad substrate scope and good functional group tolerance. Catalytic amount of Bi(OTf)3 is used as co-catalyst to improve the activity and selectivity of the reactions. A variety of esters are obtained in yields of 43–96%.
- Hu, Yongke,Li, Bindong
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p. 7301 - 7307
(2017/11/29)
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- Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
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2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
- Rajan
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p. 287 - 291
(2015/01/30)
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- Base-catalyzed retro-Claisen condensation: A convenient esterification of alcohols via C-C bond cleavage of ketones to afford acylating sources
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The base-catalyzed esterification of alcohols via retro-Claisen condensation has been demonstrated for the first time. A variety of alcohols including aryl- and heteroaryl methanols as well as aliphatic ones underwent efficient acylation to give the ester products in reasonable to good yields upon isolation. Not only conventional 1,3-diketones but also strong electron-withdrawing group containing acetophenones could serve as the acylating suppliers. The synthetic protocol is operationally simple and adaptable to a broad substrate scope. It complements the existed esterification via the retro-Claisen condensation, and enlarges this benign synthetic methodology.
- Xie, Feng,Yan, Fengxia,Chen, Mengmeng,Zhang, Min
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p. 29502 - 29508
(2014/08/05)
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- Copper-catalyzed highly efficient ester formation from carboxylic acids/esters and formates
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A highly efficient copper-catalyzed protocol for the synthesis of esters has been developed from formates. This protocol is applicable to reactions with either esters or acids as the substrates, and shows broad substrate scopes and high yields. This journal is the Partner Organisations 2014.
- Liu, Jun,Shao, Changdong,Zhang, Yanghui,Shi, Guangfa,Pan, Shulei
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supporting information
p. 2637 - 2640
(2014/05/06)
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- Facile and efficient gold-catalyzed aerobic oxidative esterification of activated alcohols
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A facile and efficient methodology is presented for the direct oxidative esterification of alcohols with alcohols catalyzed by NaAuCl4. Just in the presence of a low catalytic amount of base additive, the newly developed catalytic system proceeds with high selectivity and broad substrate scope under mild conditions with dioxygen or air as the environmentally benign terminal oxidant. Various alcohols including benzylic and allylic alcohols were smoothly reacted with methanol and even with long-chain aliphatic alcohols, affording the desired products in good to excellent yields (up to 95% yield). The present system showed high catalytic activity with a TOF up to 219 h-1. Kinetic studies of the reaction process provide fundamental insights into the catalytic pathway, and a possible reaction pathway was proposed based on the results of the control experiments. XPS, TEM, and UV-vis were carried out to characterize the chemical state of the Au catalyst in the present catalytic system. The results indicate that the Au nanoparticles were generated in situ and supported on K2CO3, forming a simple, recyclable and selective catalyst system for the direct oxidative esterification of alcohols. the Partner Organisations 2014.
- Wang, Lianyue,Li, Jun,Dai, Wen,Lv, Ying,Zhang, Yi,Gao, Shuang
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p. 2164 - 2173
(2014/04/17)
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- Efficient and simple approaches towards direct oxidative esterification of alcohols
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The present article describes novel oxidative protocols for direct esterification of alcohols. The protocols involve successful demonstrations of both "cross" and "self" esterification of a wide variety of alcohols. The cross-esterification proceeds under a simple transition-metal-free condition, containing catalytic amounts of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/TBAB (tetra-n-butylammonium bromide) in combination with oxone (potassium peroxo monosulfate) as the oxidant, whereas the self-esterification is achieved through simple induction of Fe(OAc)2/dipic (dipic=2,6-pyridinedicarboxylic acid) as the active catalyst under an identical oxidizing environment. One-pot oxidative esterification: A wide variety of alcohols undergo transition-metal-free (in the presence of oxone/2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)/tetra-n-butylammonium bromide (TBAB)) selective "cross" esterification in moderate to excellent yields (see Figure). The "self" esterification process has however been achieved in the presence of Fe(OAc)2/2,6-pyridinedicarboxylic acid (dipic) as the active catalytic species under a similar oxidizing environment.
- Ray, Ritwika,Jana, Rahul Dev,Bhadra, Mayukh,Maiti, Debabrata,Lahiri, Goutam Kumar
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supporting information
p. 15618 - 15624
(2016/02/18)
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- Graphite oxide as an efficient solid reagent for esterification reactions
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Esterification of organic acids with alcohols under mild conditions in high yields using graphite oxide, a readily available and inexpensive material, as an effective reagent is described.
- Mirza-Aghayan, Maryam,Rahimifard, Mahshid,Boukherroub, Rabah
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p. 859 - 864
(2014/12/10)
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- Selective oxidation of alcohols to esters using heterogeneous Co 3O4-N@C catalysts under mild conditions
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Novel cobalt-based heterogeneous catalysts have been developed for the direct oxidative esterification of alcohols using molecular oxygen as benign oxidant. Pyrolysis of nitrogen-ligated cobalt(II) acetate supported on commercial carbon transforms typical homogeneous complexes to highly active and selective heterogeneous Co3O4-N@C materials. By applying these catalysts in the presence of oxygen, the cross and self-esterification of alcohols to esters proceeds in good to excellent yields.
- Jagadeesh, Rajenahally V.,Junge, Henrik,Pohl, Marga-Martina,Radnik, Joerg,Brueckner, Angelika,Beller, Matthias
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supporting information
p. 10776 - 10782
(2013/08/23)
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- A facile and efficient protocol for esterification and acetalization in a PEG1000-D(A)IL/toluene thermoregulated catalyst-media combined systems
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A novel efficient and recyclable temperature-dependent biphasic catalyst and reaction media combined system comprised of PEG-1000 linked dicationic acidic ionic liquid and toluene was developed and applied in esterification of aromatic acids and acetalization of aromatic aldehydes with good to excellent yields. This system is characteristic of temperature-dependent reversible biphasic property, simple and facile recyclability, high catalytic activity and extensive substrate and reaction adaptability.
- Wang, Yinglei,Zhi, Huizhen,Luo, Jun
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- Catalysis studies of macroreticular polystyrene cation-exchange resin with terminal perfluoroalkanesulfonic acids
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Macroreticular p-(ω-sulfonic-perfluoroalkylated) polystyrene (FPS) resin with the advantages of both sulfonic polystyrene (such as macroreticular Amberlyst-15) and perfluoroalkanesulfonic resin (such as superacidic Nafion NR50) has exhibited excellent catalytic selectivity and activity in cyclization of pseudoionone and condensation of indole. In this paper, FPS was characterized by XPS, nitrogen sorption technique, FESEM and Hammett indicator method, and employed as the solid acid catalyst in the esterification, acylation and alkylation reactions. The FPS resin showed better activity than commercial solid acid catalysts (Amberlyst-15 and Nafion NR50) owing to its high surface area and strong acidity close to superacidity.
- Lin, Zhenghuan,Guan, Chuanjin,Huang, Limei,Wang, Wen,Ling, Qidan,Zhao, Chengxue
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p. 261 - 266
(2013/07/27)
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- Zinc-catalyzed oxidative esterification of aromatic aldehydes
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A general and efficient protocol for the oxidative esterification of aldehydes has been developed. By using 10 mol % of ZnBr2 and 4 equiv of H2O2, 21 examples of esters were produced in good to excellent yields. Both electron-donating and electron-withdrawing functional groups are tolerable under our reaction conditions.
- Wu, Xiao-Feng
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experimental part
p. 3397 - 3399
(2012/07/30)
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- General and selective palladium-catalyzed oxidative esterification of alcohols
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Selectively esterified: Primary alcohols react with dioxygen as a benign oxidant in a palladium-catalyzed oxidative esterification (see scheme). The corresponding aldehydes and esters are formed highly selectively depending on the catalyst system. The reactions take place in the presence of commercially available ligands without the need for additional organic hydrogen acceptors. Copyright
- Gowrisankar, Saravanan,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 5139 - 5143
(2011/06/25)
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- Nickel-Catalyzed reductive cross-Coupling of unactivated alkyl halides
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A Ni-catalyzed reductive approach to the cross-coupling of two unactivated alkyl halides has been successfully developed. The reaction works efficiently for primary and secondary halides, with at least one being bromide. The mild reaction conditions allow for excellent functional group tolerance and provide the C(sp3)-C(sp3) coupling products in moderate to excellent yields.
- Yu, Xiaolong,Yang, Tao,Wang, Shulin,Xu, Hailiang,Gong, Hegui
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supporting information; experimental part
p. 2138 - 2141
(2011/06/22)
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- Esterifications of carboxylic acids and alcohols catalyzed by Al 2(SO4)3 · 18H2O under solvent-free condition
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Esterifications of equimolar mixture of carboxylic acids and alcohols can be effectively catalyzed by Al2(SO4)3 · 18H2O under solvent-free condition. The esterification catalyzed by Al2(SO4)3 · 18H2O is a promising green method thanks to no need of organic solvent, no pollution, no causticity and ease to handle after reaction. This catalyst is of a low toxicity (usually it is used as purifying agent for drinking water), low-cost compound and is easily separated from the reaction mixture by simple filtration. Moreover, the catalyst can be recycled for the further esterification and the conversion does not evidently decrease.
- Gang, Li,Wenhui, Pang
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experimental part
p. 559 - 565
(2011/01/07)
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- Potassium phosphate / benzyltriethylammonium chloride as efficient catalytic system for transesterification
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Potassium phosphate (K3PO4) in the presence of benzyltriethylammonium chloride have been found to catalyses the transesterifications of a wide variety of aliphatic and aromatic esters with primary and secondary alcohols affording the corresponding esters in good-to-excellent yields.
- Cepanec, Ivica,Zivkovic, Andreja,Bartolincic, Anamarija,Mikuldas, Hrvoje,Litvic, Mladen,Merkas, Sonja
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experimental part
p. 519 - 523
(2010/01/07)
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- An unexpected diethyl azodicarboxylate-promoted dehydrogenation of tertiaryamine and tandem reaction with sulfonyl azide
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It is shown here for the first time that diethyl azodicarboxylate promotes dehydrogenation of tertiaryamines to afford enamines, which subsequently take place in tandem reactions with sulfonyl azides to give the N-sulfonyl amidine derivatives. A number of different substituted tertiaryamines and sulfonyl azides can successfully be coupled, and several functionalized groups are tolerated in this system. The reaction described here is mild, general, and efficient, thus providing an extremely preferable method for synthesis of a variety of N-sulfonyl amidine derivatives. Copyright
- Xu, Xiaoliang,Li, Xiaonian,Ma, Lei,Ye, Ning,Weng, Bojie
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supporting information; experimental part
p. 14048 - 14049
(2009/03/11)
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- Iron(III) chloride-promoted direct conversion of aryl/alkyl cyanides to esters
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Aryl/alkyl cyanides were quickly converted into the corresponding esters in the presence of iron(III) chloride in refluxing alcohols with very good yields. Copyright Taylor & Francis Group, LLC.
- Srinivasan,Rao, K. Srinivasa,Jayachitra,Ralte, Samuel L.
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p. 2883 - 2886
(2007/10/03)
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- A fast and simple method for the acylation of alcohols with acid chlorides promoted by metallic samarium
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Acylation of primary, secondary, allyl and benzyl alcohols with acid chlorides promoted by samarium metal under neutral condition gave carboxylic acid esters in good to excellent yields. Acylation of a tertiary alcohol did not occur under the same reaction conditions.
- Jia, Xue-Shun,Wang, Hai-Long,Huang, Qing,Kong, Ling-Long,Zhang, Wei-He
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p. 135 - 138
(2007/10/03)
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- Fe2(SO4)3·xH2O in synthesis: A convenient and efficient catalyst for the esterification of aromatic carboxylic acids with alcohols
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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
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p. 607 - 611
(2007/10/03)
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- Rearrangement of Aromatic Acetals Over Solid Acid Catalysts
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The reactions of aromatic acetals (1a-6a) catalysed by aluminium phosphate (AP) yield the corresponding esters (b), ethers (c) and the parent aldehydes (d).Similar reactions over aluminium sulphate (AS) give only esters (b) and the aldehydes (d).Probable mechanisms have been suggested for the reactions.The catalysts have been characterized by various studies.The specific poisoning of the catalysts have been done with NH3 and CO2 and the product formation on the poisoned catalyst provides support to the suggested mechanisms.
- Xavier, N.,Arulraj, S. J.
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p. 519 - 522
(2007/10/02)
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- ALKYLATION DES IONS CARBOXYLATES PAR LES SELS DE SULFONIUM: INFLUENCE DES SELS DE CUIVRE
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Sulfonium salts are extremely powerful alkylating agents, particularly in the two-phase technique both solid-liquid and liquid-liquid.Alkylation of carboxylate salts by sulfonium salts does not show very large dependence on ratio of reactivities of various groups attached to the sulfur and mixtures of esters are often obtained.In the presence of copper(I) salts, there is a strong acceleration of the reaction of allylic sulfonium salts and it becomes very selective in favour of the unsaturated residues.Prenyl sulfonium salts, which react very eficiently through the α-position in the absence of copper salts, give exclusively tertiary esters when a catalytic amount of copper bromide is present.
- Badet, B.,Julia, M.,Ramirez-Munoz, M.,Sarrazin, C. A.
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p. 3111 - 3126
(2007/10/02)
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- Removal of stannic chloride
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Stannic chloride is removed from organic solvent-based waste streams by precipitating the salt as a dimethyl sulfoxide complex.
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- H-TRANSFER CATALYSIS WITH Ru3(CO)12
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Ru3(CO)12 , in the presence of tolane, catalyses the formation of esters from the following three systems: alcohol + aldehyde, alcohol and aldehyde.
- Blum, Y.,Reshef, D.,Shvo, Y.
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p. 1541 - 1544
(2007/10/02)
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