- Ultra-high surface area functional porous polymers by emulsion templating and hypercrosslinking: Efficient nucleophilic catalyst supports
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The action is at the surface: Ultra-high surface area emulsion templated porous polymers are prepared by the hypercrosslinking method. Control of the extent of conversion of benzyl chloride groups leaves residual accessible functionality for subsequent im
- Pulko, Irena,Wall, Jennifer,Krajnc, Peter,Cameron, Neil R.
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- Insight into the Mechanism of the Acylation of Alcohols with Acid Anhydrides Catalyzed by Phosphoric Acid Derivatives
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Insight into the mechanism of a safe, simple, and inexpensive phosphoric acid (H3PO4)-catalyzed acylation of alcohols with acid anhydrides is described. The corresponding in situ-generated diacylated mixed anhydrides, unlike traditionally proposed monoacylated mixed anhydrides, are proposed as the active species. In particular, the diacylated mixed anhydrides act as efficient catalytic acyl transfer reagents rather than as Br?nsted acid catalysts simply activating acid anhydrides. Remarkably, highly efficient phosphoric acid (1-3 mol %)-catalyzed acylation of alcohols with acid anhydrides was achieved and a 23 g scale synthesis of an ester was demonstrated. Also, phosphoric acid catalyst was effective for synthetically useful esterification from carboxylic acids, alcohols, and acid anhydride. Moreover, with regard to recent developments in chiral 1,1′-bi-2-naphthol (BINOL)-derived phosphoric acid diester catalysts toward asymmetric kinetic resolution of alcohols by acylation, some phosphate diesters were examined. As a result, a 31P NMR study and a kinetics study strongly supported not only the acid-base cooperative mechanism as previously proposed by other researchers but also the mixed anhydride mechanism as presently proposed by us.
- Hayashi, Hiroyuki,Yasukochi, Shotaro,Sakamoto, Tatsuhiro,Hatano, Manabu,Ishihara, Kazuaki
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p. 5197 - 5212
(2021/04/12)
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- Isopropenyl acetate: A cheap and general acylating agent of alcohols under metal-free conditions
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Functionalized primary, secondary and tertiary alcohols are efficiently acetylated by isopropenyl acetate and catalytic p-TsOH.
- Temperini, Andrea,Minuti, Lucio,Morini, Tommaso,Rosati, Ornelio,Piazzolla, Francesca
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p. 4051 - 4053
(2017/09/27)
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- Lewis basic ionic liquid as an efficient and facile catalyst for acetylation of alcohols, phenols, and amines under solvent-free conditions
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The Lewis basic ionic liquid 1,8-diazabicyclo[5.4.0]undec-7-en-8-ium acetate was employed for the acetylation of various phenols, alcohols, and amines in good-to-excellent yields at 50 C under solvent-free conditions in a short time. Compared with existing methods based on conventional catalysts and toxic solvents, the reported method is simple, mild and environmentally viable. Furthermore, the ionic liquid was conveniently separated from the products and easily recycled to catalyze other acetylation reactions with excellent yields. .
- Ji, Li,Qian, Chao,Chen, Xin-Zhi
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p. 369 - 374
(2013/05/21)
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- Iron(III) tosylate catalyzed acylation of alcohols, phenols, and aldehydes
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Iron(III) p-toluenesulfonate (tosylate) is an efficient catalyst for acetylation of alcohols, phenols, and aldehydes. The acetylation of 1° and 2° alcohols, diols, and phenols proceeded smoothly with 2.0 mol % of catalyst. However, the reaction worked well with only a few 3° alcohols. The methodology was also applicable to the synthesis of a few benzoate esters but required the use of 5.0 mol % catalyst. Aldehydes could also be converted into the corresponding 1,1-diesters (acylals) under the reaction conditions. Iron(III) tosylate is an inexpensive, and easy to handle, commercially available catalyst.
- Baldwin, Neil J.,Nord, Anna N.,O'Donnell, Brendan D.,Mohan, Ram S.
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p. 6946 - 6949
(2013/01/15)
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- Simple and efficient method for acetylation of alcohols, phenols, amines, and thiols using anhydrous NiCl2 under solvent-free conditions
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Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac2O) in the presence of 0.1mol% (13mg) anhydrous NiCl2, an inexpensive and easily available catalyst, is described. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.
- Meshram, Gangadhar,Patil, Vishvanath D.
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experimental part
p. 4384 - 4395
(2010/04/29)
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- Development of more potent 4-dimethylaminopyridine analogues
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The syntheses of bicyclic diaminopyridines 3 and 4 and tricyclic triaminopyridines 5 and 6, two novel series of nucleophilic catalysts, are described. Arguments are made for predicting the superiority of these catalysts over DMAP and even 2, the best esterification catalyst reported to date. The efficiencies of DMAP, PPY, and 2-6 in catalyzing the esterification of tertiary alcohols were compared. As predicted, 5 and 6 were about 6-fold more effective than DMAP and slightly better than 2.
- Singh, Satwinder,Das, Goutam,Singh, Om V.,Han, Hyunsoo
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p. 401 - 404
(2008/02/12)
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- A novel 3-nitrobenzeneboronic acid as an extremely mild and environmentally benign catalyst for the acetylation of alcohols under solvent-free conditions
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A novel 3-nitrobenzeneboronic acid is found to catalyse efficiently the acetylation of a wide range of alcohols as well as phenols with acetic anhydride in good to excellent yields at room temperature under solvent-free conditions. The reactions are clean and the catalyst is mild such that highly sensitive functional groups including oximes are stable to the reaction conditions.
- Tale,Adude
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p. 7263 - 7265
(2007/10/03)
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- A mild and efficient method for the acetylation of alcohols
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The acetylatioh of alcohols has been carried out efficiently in the presence of a catalytic amount of Zr(HSO4)4. All reactions are performed at room temperature and under heterogeneous conditions in good to high yields.
- Shirini,Zolfigol,Safari
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p. 201 - 203
(2007/10/03)
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- Effects of polymer architecture and nanoenvironment in acylation reactions employing dendritic (Dialkylamino)pyridine catalysts
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The role of architecture and nanoenvironment in the catalytic properties of dendritic polymers containing 4-(dialkylamino)pyridines was investigated in the context of acylation reactions employing sterically demanding tertiary alcohols as substrates. Frechet-type benzyl ether and aliphatic ester dendrimers were prepared in a convergent manner from a common trivalent core containing three DMAP groups while a linear polymer was dendronized with aliphatic esters using a divergent growth scheme. Catalysis experiments clearly indicate that nanoenvironment plays the dominant role in determining the activity of the polymer catalysts, with the polyester platform being superior to the benzyl ether. Polymer architecture played little or no role in affecting catalysis. With respect to molecular transport and catalysis, this represents the first comparative study of the effect of architecture and nanoenvironment using structurally similar dendritic materials.
- Helms, Brett,Liang, Catherine O.,Hawker, Craig J.,Frechet, Jean M. J.
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p. 5411 - 5415
(2008/02/01)
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- Zirconiuni(IV) chloride as a new, highly efficient, and reusable catalyst for acetylation of phenols, thiols, amines, and alcohols under solvent-free conditions
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Zirconium(IV) chloride has been found to be a new, highly efficient, and reusable catalyst for acetylation of structurally diverse phenols, thiols, amines, and alcohols under solvent-free condtions. Acetylation of sterically hindered and electron deficient phenols is achieved in excellent yields with stoichiometric amounts of Ac2O at room temperature. Acid-sensitive alcohols undergo acetylation with excellent chemoselectivity without competitive side reactions such as dehydration or rearrangement. The mild Lewis acid property of the catalyst enables the acetylation to be carried out with optically active substrates without any detrimental effect on the optical purity.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 627 - 630
(2007/10/03)
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- Al(HSO4)3 as an efficient catalyst for the acetylation of alcohols in solution and under solvent free conditions
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Alcohols are acetylated in a mild, clean, and efficient reaction with acetic anhydride in the presence of a catalytic amount of Al(HSO 4)3 in solution and under solvent free conditions. All reactions were performed at room temperature in good to high yields. Springer-Verlag 2003.
- Shirini, Farhad,Zolfigol, Mohammad A.,Abedini, Masoumeh
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p. 279 - 282
(2007/10/03)
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- Copper(II) Tetrafluoroborate-Catalyzed Acetylation of Phenols, Thiols, Alcohols, and Amines
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Copper(II) tetrafluoroborate efficiently catalyzes acetylation of structurally diverse phenols, alcohols, thiols, and amines with stoichiometric amounts of Ac2O under solvent-free conditions at room temperature. Acid-sensitive alcohols are smoothly acetylated without competitive side reactions. The reaction is influenced by the steric and electronic factors associated with the substrate as well as the anhydride. Acetylation of a sterically hindered substrate requires excess of anhydride and longer time. Acylation with less electrophilic anhydrides affords poor to moderate yields.
- Chakraborti, Asit K.,Gulhane, Rajesh,Shivani
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p. 111 - 115
(2007/10/03)
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- Bismuth Oxide Perchlorate as a Highly Efficient Catalyst for Heteroatom Acylation under Solvent-Free Conditions
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Bismuth oxide perchlorate efficiently catalyzes the acetylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Sterically hindered and electron deficient phenols are acetylated in excellent yields with stoichiometric amounts of Ac2O at room temperature. Acylation of acid-sensitive alcohols is carried out efficiently without competitive side reactions. Optically active substrates are acetylated without any detrimental effect on the optical purity.
- Chakraborti, Asit K.,Gulhane, Rajesh,Shivani
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p. 1805 - 1808
(2007/10/03)
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- Indium(III) chloride as a new, highly efficient, and versatile catalyst for acylation of phenols, thiols, alcohols, and amines
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Indium(III) chloride efficiently catalyses the acylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Acid sensitive alcohols are smoothly acylated without competitive side reactions. Acylation of 2-hydroxynaphthalene is carried out with carboxylic acids adopting the mixed anhydride protocol using trifluoroacetic anhydride.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 6749 - 6753
(2007/10/03)
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- Lithium trifluoromethanesulfonate (LiOTf) as a recyclable catalyst for highly efficient acetylation of alcohols and diacetylation of aldehydes under mild and neutral reaction conditions
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A variety of alcohols and aldehydes were reacted with acetic anhydride at room temperature in the presence of a catalytic amount of lithium triflate (LiOTf) to produce the corresponding esters and 1,1-diacetates, respectively, in good to excellent yields under essentially neutral reaction conditions. Sensitive functional groups such as PhCO2-, OMe, and OTBDMS ethers survived intact under the described reaction conditions.
- Karimi, Babak,Maleki, Jafar
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p. 4951 - 4954
(2007/10/03)
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- Perchloric acid adsorbed on silica gel as a new, highly efficient, and versatile catalyst for acetylation of phenols, thiols, alcohols, and amines
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Perchloric acid adsorbed on silica gel efficiently catalyses acetylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 1896 - 1897
(2007/10/03)
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- Silica chloride as a mild and efficient reagent for acetylation of alcohols
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A variety of alcohols underwent acetylation with acetic anhydride in the presence of silica chloride. All reactions were performed at room temperature and under completely heterogeneous conditions in good to high yields.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Khaleghi, Mahroo
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p. 1999 - 2002
(2007/10/03)
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- Fluoroboric acid adsorbed on silica gel as a new and efficient catalyst for acylation of phenols, thiols, alcohols, and amines
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Fluoroboric acid supported on silica gel efficiently catalyzes acylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Acid-sensitive alcohols are smoothly acylated without competitive side reactions.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 3521 - 3525
(2007/10/03)
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- Preparation of enantiomerically pure pyridyl amino acids from serine.
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A range of substituted pyridyl amino acids have been prepared by palladium catalysed cross-coupling of serine-derived organozinc reagents with differently substituted halopyridines. Following this procedure a DMAP analogue has been synthesised and used as
- Tabanella, Stefania,Valancogne, Ingrid,Jackson, Richard F W
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p. 4254 - 4261
(2007/10/03)
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- Acetylation and formylation of alcohols in the presence of silica sulfuric acid
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Alcohols are converted to esters in a mild, clean, and efficient reaction with acetic and formic acids in the presence of silica sulfuric acid. All reactions were performed under mild and completely heterogeneous conditions in refluxing n-hexane.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Mohammadi, Kamal
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p. 1617 - 1621
(2007/10/03)
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- Soluble polymer-supported catalysts containing azo dyes
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(equation presented) Azo benzene derivatives were incorporated into soluble polymer-bound catalysts by two different approaches. The first was to attach the dye to the polymer-bound catalysts, using the dye as an innocent spectator to study the phase preference, concentration, and recoverability of a catalyst. The second approach used an azo dye as a ligand to form an effective soluble polymer-bound Pd(II) catalyst for Heck reactions.
- Bergbreiter, David E.,Osburn, Philip L.,Li, Chunmei
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p. 737 - 740
(2007/10/03)
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- N-bromosuccinimide (NBS), a novel and highly effective catalyst for acetylation of alcohols under mild reaction conditions
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A variety of alcohols were acetylated in good to excellent yields with acetic anhydride in the presence of a catalytic N-bromosuccinimide (NBS) in CH2Cl2 and at room temperature. The reactions are clean and almost in all cases no detectable byproduct were observed.
- Karimi,Seradj
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p. 519 - 520
(2007/10/03)
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- Heterogeneous catalysis in acetylation of alcohols and phenols promoted by zirconium sulfophenyl phosphonate
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Layered zirconium sulfophenyl phosphonate was found to be an efficient heterogeneous catalyst for the acetylation of alcohols and phenols.
- Curini, Massimo,Epifano, Francesco,Marcotullio, Maria Carla,Rosati, Ornelio,Rossi, Monia
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p. 1319 - 1329
(2007/10/03)
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- Synthesis of C2-symmetric analogues of 4-(pyrrolidino)pyridine: New chiral nucleophilic catalysts
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The syntheses of a series of enantiomerically pure C2-symmetric 4-(pyrrolidino)pyridine (PP Y) derivatives by SNAr of 4-halo-/4-phenoxypyridines and by cyclocondensation from 4-aminopyridine are described. Preliminary results pertaining to their use as catalysts for acylative kinetic resolution of 1-phenylethanol are also presented. A single-crystal X-ray analysis of PPY If is reported. The Royal Society of Chemistry 2000.
- Spivey, Alan C.,Maddaford, Adrian,Fekner, Tomasz,Redgrave, Alison J.,Frampton, Christopher S.
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p. 3460 - 3468
(2007/10/03)
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- Liquid phase acylation of alcohols with acetic acid over zeolites
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The liquid phase acylation of primary and secondary alcohols were carried out with acetic acid in the presence of zeolites. LaY zeolite is found to be the best catalyst.
- Narender,Srinivasu,Kulkarni,Raghavan
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p. 1887 - 1893
(2007/10/03)
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- Configurationally Stable Biaryl Analogues of 4-(Dimethylamino)pyridine: A Novel Class of Chiral Nucleophilic Catalysts
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A short synthetic approach toward a novel class of chiral nucleophilic catalysts, the dissymmetry of which stems from restricted rotation about an Ar-Ar bond, has been developed. The key steps of the synthesis include preparation of a nucleophilic 1-methyl-2-pyrrolino[3,2-c]pyridine core 16 by ortho-lithiation and creation of the biaryl axes via Suzuki cross-coupling reactions. Comparative HPLC studies of racemization for configurationally labile biaryls 31, 38, and 43 containing 1-methyl-2-pyrrolino[3,2-c]pyridine, 4-(dimethylamino)pyridine, and 4-(1-pyrrolidino)pyridine cores, respectively, have demonstrated that a pyrrolidino substituent ortho to the biaryl axis is optimal for slowing Ar-Ar rotation. Biaryls containing all three cores have been shown to retain DMAP-like catalytic activity in the acylation of a hindered alcohol. Biaryls 55 and 56, which are configurationally stable at ambient temperature, have also been prepared via modification of configurationally labile derivatives. Compounds 55 and 56 in optically pure form should provide a useful starting point for studies on catalytic asymmetric acyl transfer using atropisomeric analogues of DMAP.
- Spivey, Alan C.,Fekner, Tomasz,Spey, Sharon E.,Adams, Harry
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p. 9430 - 9443
(2007/10/03)
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- An Extremely Powerful Acylation Reaction of Alcohols with Acid Anhydrides Catalyzed by Trimethylsilyl Trifluoromethanesulfonate
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Trimethylsilyl trifluoromethanesulfonate is an excellent catalyst for the acylation of alcohols with acid anhydrides. Highly functionalized primary, secondary, tertiary, and allylic alcohols, and phenols, were acylated cleanly and efficiently and in a fraction of the time used under the standard DMAP conditions.
- Procopiou, Panayiotis A.,Baugh, Simon P.D.,Flack, Stephen S.,Inglis, Graham G.A.
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p. 2342 - 2347
(2007/10/03)
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- Synthesis of atropisomeric analogues of DMAP
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A method for the preparation of 7-aryl derivatives of N-methyl-5- azaindolinee involving Suzuki cross-coupling is described. Certain biaryls prepared in this manner exhibit atropisomerism. In particular, azaindoline 11 is shown to be configurationally sta
- Spivey, Alan C.,Fekner, Tomasz,Adams, Harry
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p. 8919 - 8922
(2007/10/03)
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- The oxidation of alkanes with dimethyldioxirane; a new mechanistic insight
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Primary kinetic isotope effects were measured for the oxidation of cyclohexane and methylcyclohexane with DMDO in solution and in the gas phase. These experiments suggest an electrophilic oxygen insertion mechanism for the oxidation of alkanes by DMDO.
- Asensio, Gregorio,Mello, Rossella,Gonzalez-Nunez, M. Elena,Boix, Carmen,Royo, Jorge
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p. 2373 - 2376
(2007/10/03)
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- An Efficient Acylation of Tertiary Alcohols with Isopropenyl Acetate Mediated by an Oxime Ester and Cp*2Sm(thf)2
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An efficient method for the acylation of tertiary alcohols with isopropenyl acetate (1) by the use of an oxime and Cp*2Sm(thf)2 as catalyst was developed. Thus, various types of tertiary alcohols could be acylated with 1 in the presence of a catalytic amount of cyclohexanone oxime acetate (2) and Cp*2Sm(thf)2 under mild conditions to form the corresponding acetates in excellent yields. Acid-sensitive terpene alcohols such as linalool were successfully acetylated by the present method to give acetyl linalool in quantitative yield. This method enables an alternative acylation of tertiary alcohols under acid-free conditions.
- Tashiro, Daisuke,Kawasaki, Yumi,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 8141 - 8144
(2007/10/03)
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- Scandium trifluoromethanesulfonate as an extremely active Lewis acid catalyst in acylation of alcohols with acid anhydrides and mixed anhydrides
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Scandium trifluoromethanesulfonate (triflate), which is commercially available, is a practical and useful Lewis acid catalyst for acylation of alcohols with acid anhydrides or the esterification of alcohols by carboxylic acids in the presence of p-nitrobenzoic anhydrides. The remarkably high catalytic activity of scandium triflate can be used for assisting the acylation by acid anhydrides of not only primary alcohols but also sterically-hindered secondary or tertiary alcohols. The method presented is especially effective for selective macrolactonization of ω-hydroxy carboxylic acids.
- Ishihara, Kazuaki,Kubota, Manabu,Kurihara, Hideki,Yamamoto, Hisashi
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p. 4560 - 4567
(2007/10/03)
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- The Reaction between Acyl Halides and Alcohols: Alkyl Halide vs. Ester Formation
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In the reaction between an acyl halide and an alcohol the thermodynamically favoured products are the free carboxylic acid and the alkyl halide.The initial reaction is, generally, the formation of an ester and HHal.When the alcohol is very prone to yield an alkyl cation upon protonation by HHal, formed H2O exhibited a superior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role.But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation.Tis final product, on the other hand, might be extremely slow to form in an SN2 reaction between the protonated ester function and the halide ion.In these instances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product.A notable exception of the situation above outlined, is given by α-hydroxy-α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y).Different systems were compared using CH2Cl2 as a solvent under strictly similar conditions.Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (a) against (RS)-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.
- Strazzolini, Paolo,Giumanini, Angelo G.,Verardo, Giancarlo
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p. 217 - 254
(2007/10/02)
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- Cobalt(II) Chloride Catalyzed Acylation of Alcohols with Acetic Anhydride: Scope and Mechanism
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Cobalt(II) chloride catalyzes the acetylation of a variety of alcohols with acetic anhydride in excellent yield.Primary hydroxyl groups can be selectively acylated in the presence of secondary and tertiary ones while the secondary hydroxyl groups can be preferentially acetylated in the presence of tertiary ones.Tertiary alcohols have been found to give ketones, acetoacetates, olefins, and diketene in addition to the acetate.The β-hydroxy esters and ketones can be acylated under these conditions without any elimination, and this reaction has been compared with 4-(dimethylamino)pyridine (DMAP)-mediated acylations where elimination of the resulting β-acetoxy carbonyl compound is observed.A detailed investigation of the acylation of tertiary alcohols has revealed that these reactions proceed via a tertiary alkoxy radical and ketene.A mechanism for these acylations is proposed by invoking an electron-transfer process.
- Iqbal, Javed,Srivastava, Rajiv Ranjan
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p. 2001 - 2007
(2007/10/02)
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- Pentaalkylguanidines as etherification and esterification catalysts
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Several pentaalkylguanidines have been prepared and found to be superior catalysts for the preparation of aryl and aralkyl ethers from carbonates and for the methylation of phenols with dimethylcarbonate.They also act as effective catalysts for esterification of acids with alkyl chloroformates but not for the acetylation of tertiary alcohols with acetic anhydride.
- Barcelo, Gerard,Grenouillat, Denis,Senet, Jean-Pierre,Sennyey, Gerard
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p. 1839 - 1848
(2007/10/02)
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- Palladium-catalyzed allylic acetoxylation: an exploratory study of the influence of added acids
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In order to investigate the possibility of improving the selectivity in palladium-catalyzed acetoxylation of substituted cycloalkenes and linear alkenes, the influence of added strong acids has been studied.It was found that the product selectivity can be increased in some cases, but also that side reactions lower the total yields when trifluoroacetic or stronger acids are used.The improvement of the selectivity may possibly be due to a change in mechanism for the acetoxylation.
- Akermark, Bjoern,Hansson, Sverker,Rein, Tobias,Vagberg, Jan,Heumann, Andreas,Baeckvall, Jan-Erling
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p. 433 - 444
(2007/10/02)
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- A New Acylation Catalyst
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Cobalt(II) chloride catalyses the acylation of alcohols and amines with anhydrides in excellent yields.
- Ahmad, Saeed,Iqbal, Javed
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p. 114 - 115
(2007/10/02)
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- 13C NMR DETERMINATION OF THE CONFORMATIONAL EQUILIBRIA IN THE ACETATES, BENZOATES AND N-PHENYLCARBAMATES OF 1-METHYLCYCLOHEXANOL AND CYCLOHEXANOL
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Thermodynamic parameters for the conformational equilibria in the acetates, benzoates and N-phenylcarbamates of 1-methylcyclohexanol and cyclohexanol have been determined using low temperature natural abundance 13C nmr, from which -ΔG0 values at room temperature and above are obtained.Good agreement between these values and those determined at the higher temperatures using Eliel's method is found, providing care is exercised in correcting the chemical shifts of the model compounds used to the shifts of pure conformers of the 1,1-disubstituted cyclohexanes.Calculated values for -ΔG0 agree reasonably with experimental values with the exception of that for the 1-methylcyclohexyl N-phenylcarbamate.The effect of non polar solvent changes is minimal, but greater for CD3OD.
- Jordan, Elizabeth A.,Thorne, Melanie P.
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- Electrophilic Cleavage of Cyclopropanes. Acetolysis of Bicyclic and Tricyclic Cyclopropanes
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The acetolysis of a series of bicycloalkanes and propellanes has been studied.The effect of ring strain, caused by changing ring size or introducing a trans-ring fusion, on the rate and products of the reaction has been examined.No correlation was found between rates of acetolysis and strain energy relief, but with the exception of propellane, there is a rough correlation with ionization potentials.The degree of polarization of the C-C bonds in the presence of a proton correlates very well with reactivity and is a controlling factor for the acetolysis rates.The importance of the energies of unoccupied orbitals with the appropriate symmetry in controlling electron polarization is shown by the large difference in rate of reaction between - and propellanes.
- Wiberg, Kenneth B.,Kass, Steven R.,Meijere, Armin de,Bishop, K. C.
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p. 1003 - 1007
(2007/10/02)
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- Formation of Cyclic Carbonates in the Reaction of 1,2-Ditertiary Diols with Acetic Anhydride and 4-(Dimethylamino)pyridine
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The reaction of 1,2-ditertiary diol 1a with acetic anhydride and 4-(dimethylamino)pyridine (DMAP) at high concentrations in the absence of solvent has been found to give rise to cyclic carbonate 2a.The reaction has been generalized with a few other 1,2-ditertiary diols (1b-d).Based on the different products isolated in these reactions, apart from a small amount of normal acetylation products, various mechanisms have been proposed and examined.Tertiary alcohols have been found to give monoacetoacetates in addition to the acetates, under the same conditions.Detailedinvestigations have prompted us to suggest the intermediacy of ketene and diketene in these reactions.
- Bhushan, Vidya,Chakraborty, Thushar K.,Chandrasekaran, Srinivasan
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p. 3974 - 3978
(2007/10/02)
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