- Ozonolysis of acetic acid 1-vinyl-hexyl ester in a falling film microreactor
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Ozonolysis of acetic acid 1-vinyl-hexyl ester was carried out in a falling film microreactor in a continuous fashion. The influence of reaction variables (e.g., olefin concentration, ozone initial partial pressure, gas velocity, temperature and liquid flow rate) on the product formation in the liquid phase was studied over a wide range of operating conditions. Based on the obtained results, a formal reaction scheme for the ozonolysis of acetic acid 1-vinylhexyl ester is suggested. The acetic acid 1-formyl-hexyl ester and the corresponding carbonyl oxide are the main products of the cleavage of the primary formed ozonide. The secondary ozonide acetic acid 1-[1,2,4]trioxolan-3-yl-hexyl ester is formed by consecutive reaction of the acetic acid 1-formyl-hexyl ester and the carbonyl oxide.
- Steinfeldt, Norbert,Abdallah, Radwan,Dingerdissen, Uwe,Jaehnisch, Klaus
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Read Online
- Protection of COOH and OH groups in acid, base and salt free reactions
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We report an iron-catalyzed general functional group protection method with inexpensive reagents. This environmentally benign process does not use acids or bases, and does not produce waste products. Further purification beyond filtration and evaporation is, in most cases, unnecessary. Free COOH and OH groups can be protected in a one-pot reaction.
- Zhu, Xiaotao,Qian, Bo,Wei, Rongbiao,Huang, Jian-Dong,Bao, Hongli
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supporting information
p. 1444 - 1447
(2018/04/12)
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- Proton-gradient-transfer acid complexes and their catalytic performance for the synthesis of geranyl acetate
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Special proton-gradient-transfer acid complexes (PGTACs) in which the bonded protons are not equivalent and have gradients in transfer ability, acidity, and reactivity were reported. The acidity gradient of the protons gave the PGTACs excellent catalytic activity and selectivity in the esterification of terpenols. These PGTACs are “reaction-induced self-separation catalysts” and can be easily reused. The kinetics with PGTACs as catalyst in the esterification of geraniol were also studied for use in engineering design.
- Chen, Yongle,Ding, Shiya,Zheng, Wentao,Zhang, Yiyang,Wu, Youting,Hu, Xingbang
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p. 2114 - 2121
(2017/01/16)
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- Branch-selective allylic C-H carboxylation of terminal alkenes by pd/sox catalyst
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A ligand-controlled branch-selective allylic C-H carboxylation through Pd catalysis is described. The developed catalytic system, which consists of Pd(OAc)2, sulfoxide-oxazoline (sox) as a ligand and benzoquinone as an oxidant, couples terminal alkenes and carboxylic acids to furnish the corresponding branched allylic esters with high regioselectivity.
- Kondo, Hiroki,Yu, Feng,Yamaguchi, Junichiro,Liu, Guosheng,Itami, Kenichiro
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supporting information
p. 4212 - 4215
(2014/11/07)
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- Palladium-catalyzed selective anti-markovnikov oxidation of allylic esters
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An aldol alternative: The palladium(II)-catalyzed anti-Markovnikov oxidation of allylic esters to aldehydes at room temperature provides a viable alternative to valuable cross aldol products. High regioselectivity towards the aldehyde product was achieved using the ester protecting group for the allylic alcohol. Rapid isomerization and the much higher rate of oxidation of the branched isomer result in the same product forming from both linear and branched allylic esters. Copyright
- Dong, Jia Jia,Fananas-Mastral, Martin,Alsters, Paul L.,Browne, Wesley R.,Feringa, Ben L.
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supporting information
p. 5561 - 5565
(2013/06/27)
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- Syntheses of enantiopure aliphatic secondary alcohols and acetates by bioresolution with lipase B from candida antarctica
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The lipase B from Candida antarctica (Novozym 435, CALB) efficiently catalyzed the kinetic resolution of some aliphatic secondary alcohols: (±)-4-methylpentan- 2-ol (1), (±)-5-methylhexan-2-ol (3), (±)-octan-2-ol (4), (±)-heptan-3-ol (5) and (±)-oct-1- en-3-ol (6). The lipase showed excellent enantioselectivities in the transesterifications of racemic aliphatic secondary alcohols producing the enantiopure alcohols (>99% ee) and acetates (>99% ee) with good yields. Kinetic resolution of rac-alcohols was successfully achieved with CALB lipase using simple conditions, vinyl acetate as acylating agent, and hexane as non-polar solvent.
- Ferreira, Hercules V.,Rocha, Lenilson C.,Severino, Richele P.,Porto, Andre L. M.
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p. 8955 - 8967,13
(2020/08/31)
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- N-acyl 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) tetraphenylborate salts as O-acylating agents
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Air-stable and crystalline N-acyl DBN tetraphenylborate salts have been shown to be effective O-acylating agents, reacting with both primary and secondary alcohols to give the corresponding esters in good yields. In the case of diols, the N-acyl DBN·BPh4 salts have been shown to acylate regioselectively the primary alcohol functionality in the presence of a secondary alcohol. The DBN hydrotetraphenylborate side product can be readily removed by filtration, providing the ester products without the need for further purification.
- Taylor, James E.,Williams, Jonathan M.J.,Bull, Steven D.
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experimental part
p. 4074 - 4076
(2012/08/28)
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- Highly efficient kinetic resolution of allylic alcohols with terminal double bond
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In this study, the lipase-catalyzed kinetic resolution (Novozyme 435) was employed to prepare chiral allylic alcohols and acetates with terminal double bonds in enantiomeric excesses ranging from 94 to >99 %.
- Marques, Francisco A.,Oliveira, Marcos A.,Frensch, Gustavo,Sales Maia, Beatriz Helena L. N.,Barison, Andersson,Lenz, Cesar A.,Guerrero Jr., Palimecio G.
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body text
p. 696 - 700
(2012/06/04)
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- o-benzenedisulfonimide as a soft, efficient, and recyclable catalyst for the acylation of alcohols, phenols, and thiols under solvent-free conditions: Advantages and limitations
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o-Benzenedisulfonimide turns out to be a highly efficient Bransted acid catalyst for the acylation of a number of alcohols, phenols, and thiols under a metal- and solvent-free procedure; reaction conditions are mild and yields very good. After the workup, the catalyst can be easily recovered and purified, ready to be reused, with economic and ecological advantages. Georg Thieme Verlag Stuttgart · New York.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano,Venturello, Paolo
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experimental part
p. 3625 - 3632
(2009/07/04)
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- Unified, radical-based approach for the synthesis of spiroketals
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Functionalization of S-(3-chloro-2-oxo-propyl)-O-ethyl xanthate 1 by two consecutive xanthate transfer reactions, followed by spirocyclization of the resulting dihydroxy ketones, provides a flexible and highly convergent access to diversely substituted spiroketals, containing five-, six-, and seven-membered rings.
- De Greet, Michiel,Zard, Samir Z.
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p. 1773 - 1776
(2008/02/02)
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- Atom transfer radical cyclization (ATRC) applied to a chemoenzymatic synthesis of Quercus lactones
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The natural fragrances (+)-trans whisky lactone 2 and (+)-trans cognac lactone 4, together with a minor amount of their (-)-cis stereoisomers, were prepared in 50% and 42% overall yield, respectively, starting from racemic 1-hepten-3-ol (±)-5 and 1-octen-3-ol (±)-6. The procedure involved first the enantioconvergent, lipase mediated transformation of the secondary allylic alcohols derived dichloroacetates (±)-7 and (±)-8 into the corresponding homochiral (+)-7 and (+)-8, combined with their cyclization under a transition metal catalyzed atom transfer process.
- Felluga, Fulvia,Forzato, Cristina,Ghelfi, Franco,Nitti, Patrizia,Pitacco, Giuliana,Pagnoni, Ugo Maria,Roncaglia, Fabrizio
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p. 527 - 536
(2007/10/03)
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- Aluminium dodecatungstophosphate (AlPW12O40) as a highly efficient catalyst for the selective acetylation of -OH, -SH and -NH2 functional groups in the absence of solvent at room temperature
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AlPW12O40 was found to be an effective catalyst for the selective acetylation of alcohols, thiols, and amines in the absence of solvent at room temperature.
- Firouzabadi, Habib,Iranpoor, Nasser,Nowrouzi, Farhad,Amani, Kamal
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p. 764 - 765
(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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- 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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- Enzymatic Hydrolysis of Alken- and Alkyn-3-ol Acetates in an Acetone-Water Solvent System: Effect of Unsaturation on the Enantioselectivity of Pseudomonas cepacia Lipase-catalyzed Hydrolysis
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High enentioselectivity was observed for the Pseudomonas cepacia lipase-catalyzed hydrolysis of (E)-allylic acetate 1 and propargylic acetate 2 in an acetone-water solvent system, while (E)-homoallylic acetate 3 and homopropargylic acetate 4 gave poor enantioselectivity.
- Kamezawa, Makoto,Raku, Takao,Tachibana, Hojun,Ohtani, Takehiko,Naoshima, Yoshinobu
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p. 549 - 551
(2007/10/02)
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- Energetic and Rate Effects of the Trifluoromethyl Group at C-2 and C-4 on the Aliphatic Claisen Rearrangement
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The rate of the Claisen rearrangement is accelerated by a factor of 73 over the parent system when a trifluoromethyl group is present at C-2 of allyl vinyl ether.Ground-state destabilization by the trifluoromethyl group may be responsible for this rate effect.There is little polar character in the transition state, and the transition-state structure has little carbonyl character and only moderate (ca. 1/3) bonding character between the two terminal carbons.The rate enhancement is not observed in the Cope rearrangement of the all-carbon analogue that has a trifluoromet hyl group at C-2.At C-4, the trifluoromethyl group does not bring about a significant rate effect in the Claisen rearrangement relative to the parent system; this result is in contrast to an energetic benefit of 3.5 kcal/mol enjoyed by the system when a cyano group is at C-4, which suggests that radical-stabilizing ability and not electronic-withdrawing ability is important in stabilizing the transition state.
- Gajewski, J. J.,Gee, K. R.,Jurayj, J.
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p. 1813 - 1822
(2007/10/02)
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- Allylic Oxidation of Olefins by Cobalt(III), Manganese(III), and Cerium(IV) Acetates in Acetic Acid in the Presence of Sodium Bromide
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The effect of added sodium bromide on the allylic oxidation of olefins by cobalt(III), manganese(III), and cerium(IV) acetates has been studied.Sodium bromide strongly accelerated the oxidation of cyclohexene by these oxidants to give cyclohex-2-enyl acetate in good yield.Only one product was obtained in the oxidation of cycloalkenes, but two allylic acetates were obtained in the oxidations of methyl-substituted cyclohexenes, which have two kinds of allylic hydrogen.A mechanism involving hydrogen abstraction from allylic sites by bromine radicals is suggested.
- Morimoto, Takashi,Machida, Toshinori,Hirano, Masao,Zhung, Xiumin
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p. 909 - 914
(2007/10/02)
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- Herstellung und Isomerisierung von 1-Alken-3-yl-acetaten und 2-Alken-1-yl-acetaten
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The allylic rearrangement of 1-alken-3-yl acetates in acetic acid containing sodium acetate proceeds at a slower rate but in higher yield than the rearrangement in the presence of strong proton acids.The predominant products are 2-alken-1-yl acetates. (E)-2-Hexen-1-yl acetate can be isomerized to the (Z)-isomer or rearranged to 1-hexen-3-yl acetate via the epoxide, depending upon the conditions of reduction of the epoxide.
- Garcia Martinez, Antonio,Oliver Ruiz, Manuel,Contelles, Jose Luis Marco
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p. 125 - 128
(2007/10/02)
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- METAL-CATALYZED REARRANGEMENTS OF ALLYLIC ESTERS
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It has been shown that Pd(CH3CN)2Cl2 catalyzes the rearrangement of allylic esters.Carbamates rearrange more rapidly than acetates which in turn rearrange more rapidly than carbonates.Allylic carbamates are more rapidly isomerized by Pd(CH3CN)2Cl2 than by Hg(OCOCF3)2.The rearrangement proceeds well except in cases where the central carbon of the allylic system is fully substituted.In contrast to the reported rearrangement of allylic carbamates by Hg2+ and previous reports of Pd2+-catalyzed rearrangements of allylic esters, this work showed the latter are extremely E specific; thus E allylic acetates yield equilibrium mixtures free of Z allylic isomers, under conditions in which Z allylic acetates are unreactive.This E specificity is applied to stereospecific 1,3-diene synthesis from bis E,Z-allylic acetates
- Oehlschlager, A. C.,Mishra, P.,Dhami, S.
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p. 791 - 797
(2007/10/02)
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- Electron-transfer Processes: Metal Salt Catalysed Oxidation of Olefins by Peroxydisulphate
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The reaction of simple olefins (oct-1-ene, oct-2-ene, cyclohexene, cycloheptene) with peroxydisulphate has been investigated under several conditions: (i) in aqueous medium and catalysis by AgI, FeII, and CuII; (ii) in acetic madium and catalysis by CuII, FeIII; (iii) in the presence of traps of nucleophilic alkyl radicals (protonated heteroaromatic bases and 1,4-benzoquinone either in water or in acetic acid).The catalyst and the radical trap govern the selectivity and allow a variety of new synthetic achievements.Evidence for a unified initial mechanism of electron transfer with formation of a radical cation from the olefin is reported to explain all the results.In water the radical cation gives a β-hydroxyalkyl radical, which, depending on the nature of the catalyst and the trap, can give the corresponding saturated alcohol by hydrogen abstraction, the products of CuII oxidation, or β-hydroxyalkylation of the heteroaromatic compound or 1,4-benzoquinone.In acetic acid the radical cation gives a β-acetoxyalkyl radical, which is oxidized to the corresponding allylic acetate by copper(II) acetate or trapped by the heteroaromatic base.
- Arnoldi, Claudio,Citterio, Attilio,Minisci, Francesco
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p. 531 - 542
(2007/10/02)
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- Oxidation by Cobalt(III) Acetate. Part 3. Allylic Oxidation of Various Olefins in Acetic Acid
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Allylic oxidation of various olefins with cobalt(III) acetate in acetic acid under nitrogen has been investigated.The substrates studied include allylbenzene, oct-1-and -trans-4-ene, cycloalkenes (C5-C8), and 1-and 4-methyl-cyclohexene.The reaction gave exclusively the allylic acetate as the primary product; no 1,2-addition or skeletal rearrangement product was formed in significant amount.Some mechanistic aspects of allylic oxidation are discussed.
- Hirano, Masao,Nakamura, Kouji,Morimoto, Takashi
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p. 817 - 820
(2007/10/02)
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- Enzymic Resolution of (+/-)-Acyclic Alcohols via Asymmetric Hydrolysis of Corresponding Acetates by Microorganisms
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Asymmetric hydrolysis of (+/-)-1-pentyl-2-propynyl and 1-pentyl-2-propenyl acetates by selected microorganisms produced chiral 1-octyn-3-ol and 1-octen-3-ol, respectively, with high optical purities and acetates of their antipodes.Enantioselectivity of microbial hydrolysis changed with the microorganisms used.Also, (+/-)-1-ethylhexyl acetate was asymmetrically hydrolyzed by microorganisms to give (S)-3-octanol and (R)-1-ethylhexyl acetate of relatively low optical purity and hydrolytic ratio, compared with those of (+/-)-1-pentyl-2-propynyl acetate.
- Oritani, Takayuki,Yamashita, Kyohei
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p. 2407 - 2412
(2007/10/02)
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