- Rapid and Multigram Synthesis of Vinylogous Esters under Continuous Flow: An Access to Transetherification and Reverse Reaction of Vinylogous Esters
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An environmentally benign approach for the synthesis of vinylogous esters from 1,3-diketone and its reverse reaction under continuous-flow has been developed with alcohols in the presence of inexpensive Amberlyst-15 as a catalyst. This methodology is highly selective and general for a range of cyclic 1,3-dicarbonyl compounds which gives a library of linear alkylated and arylated vinylogous esters in good to excellent yield under solvent and metal free condition. Furthermore, the long-time experiment in a continuous-flow up to 40 h afforded 8.0 g of the vinylogous ester with turnover number (TON) = 28.6 and turnover frequency (TOF) = 0.715 h-1 using Amberlyst-15 as a catalyst. Furthermore, a continuous-flow sequential transetherification of vinylogous esters with various alcohols has been achieved in high yield. Reversibly, this vinylogous ester was deprotected or hydrolyzed into ketone using environmentally benign water as a solvent and Amberlyst-15 as a catalyst under continuous-flow process.
- Mohanta, Nirmala,Chaudhari, Moreshwar B.,Digrawal, Naveen Kumar,Gnanaprakasam, Boopathy
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p. 1034 - 1045
(2019/05/24)
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- Reversible chemoselective transetherification of vinylogous esters using Fe-catalyst under additive free conditions
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An additive/Br?nsted acid/base free, highly efficient and chemoselective transetherification of electron deficient vinylogous esters and water mediated de-alkylation using an earth-abundant Fe-catalyst under very mild reaction conditions is described. This reaction is highly selective to primary alcohols over secondary alcohols, has good functional group tolerance, is scalable to gram scale and a purification free sequential transetherification in a continuous flow mode is demonstrated.
- Parvathalu, Nenavath,Agalave, Sandip G.,Mohanta, Nirmala,Gnanaprakasam, Boopathy
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p. 3258 - 3266
(2019/03/26)
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- Cyclization of 5-hexynoic acid to 3-alkoxy-2-cyclohexenones
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The one-pot cyclization of 5-hexynoic acid to produce 3-alkoxy-2- cyclohexenones proceeds in good yields (58-90%). 3-Hexynoic acid was converted to its acyl chloride with the aid of oxalyl chloride and was cyclized to 3-chloro-2-cyclohexenone upon addition of indium(III) chloride. Subsequent addition of alcohol nucleophiles led to the desired 3-alkoxy-2-cyclohexenones.
- Hylden, Anne T.,Uzelac, Eric J.,Ostojic, Zeljko,Wu, Ting-Ting,Sacry, Keely L.,Sacry, Krista L.,Xi, Lin,Jones, T. Nicholas
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experimental part
p. 1323 - 1326
(2011/11/06)
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- Zinc-mediated alkylation and acylation of 1,3-dicarbonyl compounds
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1,3-Dicarbonyl compounds undergo smooth allylation, benzylation, propargylation, and acylation with halides using metallic zinc in DMF at 60 °C to afford the corresponding allyl, benzyl, 2-propynyl, and acylated 1,3-diesters in good yields. In the case of cyclic 1,3-diketones, the corresponding enol ethers are obtained as sole products instead of C-alkylation.
- Yadav,Reddy, B. V. Subba,Mishra, Anand Kumar
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experimental part
p. 280 - 281
(2010/09/05)
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- Iron(III) tosylate in the preparation of dimethyl and diethyl acetals from ketones and β-keto enol ethers from cyclic β-diketones
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An efficient method for conversion of ketones to their corresponding dimethyl and diethyl acetals and of cyclic β-diketones into β-keto enol ethers using Fe(OTs)3 as a catalyst is described. Copyright Taylor & Francis Group, LLC.
- Mansilla, Horacio,Afonso, Maria M.
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p. 2607 - 2618
(2008/12/22)
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- An efficient conversion of β-diketones into β-keto enol ethers with P2O5/SiO2 under solvent-free conditions
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P2O5/SiO2 was found to be an efficient reagent for converting cyclic-β-diketones into their corresponding β-keto enol ethers at room temperature under solvent-free conditions.
- Cui, Zhen-Shui,Zhang, Zhan-Hui,Liu, Shu-Fen
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p. 390 - 392
(2007/10/03)
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- B(C6F5)3-catalyzed synthesis of β-keto enol ethers from β-diketones
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Efficient and practical synthesis of β-keto enol ethers from diketones catalyzed by B(C6F5)3 at room temperature has been described. Georg Thieme Verlag Stuttgart.
- Chandrasekhar,Srinivasa Rao,Ramakrishna Reddy
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p. 1471 - 1473
(2007/10/03)
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- Microwave assisted rapid synthesis of 3-alkoxy-2-cyclohexen-1-ones from 1,3-cyclohexanedione
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Synthesis of 3-alkoxy-2-cyclohexen-1-ones from 1,3-cyclohexanedione with various alcohols has been achieved under microwave irradiation conditions within 7 min.
- Murugan,Reddy
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p. 1512 - 1514
(2007/10/03)
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- Solvent free rapid synthesis of 3-alkoxycyclohex-2-en-1-one from 1,3-cyclohexanedione promoted by indium(in) chloride/silica gel
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A convenient and environmentally friendly method for the synthesis of 3-alkoxycyclohex-2-en-1-one 1 from cyclohexane-1,3-dioneonthe surface of silica gel impregnated with indium(III) chloride under microwave irradiation without any solvent has been reported CSIRO 2005.
- Murugan,Kamakshi,Reddy, Boreddy S. R.
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p. 228 - 230
(2008/02/04)
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- Tetraphenylstibonium Methoxide Promoting C-Alkylation of 2-Substituted Cyclic 1,3-Diketones
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Selective C-alkylation of 2-methyl-1,3-cyclopentanedione and 2-methyl-1,3-cyclohexanedione was performed by using tetraphenylstibonium methoxide (Ph4SbOMe).The presence of a substituent at the 2-position was essential for C-alkylation.
- Fujiwara, Masahiro,Hitomi, Kazuhisa,Baba, Akio,Matsuda, Haruo
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p. 875 - 876
(2007/10/02)
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- The synthesis of mycophenolic acid
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A new synthesis of mycophenolic acid 1, has been accomplished using silyloxy-1,3-cyclohexadiene 9 which undergoes cycloaddition to dimethyl acetylenedicarboxylate and subsequent elimination of ethylene (Alder-Rickert reaction) to give the trisubstituted dimethyl phthalate 11. After conversion of 11 to phthalide 16, the (E)-4-methyl-4-hexenoic acid side-chain was constructed via an orthoester Claisen rearrangement using allylic alcohol 19 and triethyl orthoacetate.
- Patterson, John W.
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p. 4789 - 4798
(2007/10/02)
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- Intramolecular Photocycloaddition Reactions of 3-(2-Propenoxy)cyclopent-2-en-1-ones and 3-(2-Propenoxy)cyclohex-2-en-1-ones
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The 3-oxy-1,5-hexadienones 4a, 4b, 5a, and 5b undergo intramolecular photocycloaddition reactions with quantum yields ranging from 0.2 to 0.002.In general, oxa substitution decreases the quantum yields and favors the formation of crossed closure pro
- Matlin, Albert R.,Turk, Benjamin E.,McGarvey, David J.,Manevich, Alejandro A.
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p. 4632 - 4638
(2007/10/02)
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- Photoreactions of Enones with Amines - Cyclization of Unsaturated Enones and Reductive Ring Opening by Photoinduced Electron Transfer (PET)
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Photolysis of the unsaturated enones 1 yields cycloaddition products 2 and 3 with varying regioselectivity.Under electron transfer conditions (PET) spirocyclic products 4 are formed.The straight cycloaddition products 2b, c, f are converted to the spirocyclic products 4b, c, f under the same reaction conditions.The cyclobutane 5 and cyclopropane 11 also undergo this new reductive ring opening reaction, while the stabilized system 7 is converted to reduced ring-enlarged triquinane 10 which may be interesting in natural product synthesis. - Irradiation of 2-cyclohexen-1-one (14) in the presence of N,N-dimethylallylamine (15) leads to the decahydroisoquinoline 18.A mechanism involving radical intermediates is discussed. Key Words: Photoinduced electron transfer / Cyclization / Ring opening / Enones
- Mattay, Jochen,Banning, Anja,Bischof, Eric W.,Heidbreder, Andreas,Runsink, Jan
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p. 2119 - 2128
(2007/10/02)
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- RADICAL ANIONIC CYCLIZATION REACTIONS VIA PHOTOCHEMICALLY INDUCED ELECTRON TRANSFER
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Irradiating cyclohexenones containing an olefinic side chain under electron transfer-conditions (PET) leads to new spirocyclic products 3, as well as -cycloaddition products 2.A new reductive cyclobutane ring opening allows photochemical conversion o
- Bischof, Eric W.,Mattay, Jochen
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p. 7137 - 7140
(2007/10/02)
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- INTRAMOLECULAR PHOTOCYCLOADDITION REACTIONS OF 1-ACYL-3-OXA-1,5-HEXADIENES
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The regioselectivity of the intramolecular photocycloadditions of 1-Acyl-3-oxa-1,5-hexadienes appears, in general, to follow "rule of five" closure and give annelated 2-oxa-bicyclohexanes.
- Matlin, Albert R.,McGarvey, David J.
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p. 5087 - 5090
(2007/10/02)
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