- Synthesis of 2,3-Bis(acetoxymethyl)bicyclohepta-2,5-diene and its Use in Palladium-Catalyzed Elimination
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The synthesis of a novel polyfunctional bicyclic compound, 2,3-bis(acetoxymethyl)bicyclohepta-2,5-diene (1), is reported.The obtained prochiral synthon may be considered as a useful substrate on the route toward natural products and compounds of pharmaceutical interest.Submission of 1 to palladium-catalyzed elimination affords vinylic acetate 3, 2-methylene-3-(acetoxyvinyl)bicyclohept-5-ene, in excellent yields.
- Muchow, G.,Brunel, J. M.,Maffei, M.,Buono, G.
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- Unusual reactivity of acetate versus carbonate in palladium-catalyzed nucleophilic substitutions: A strong silicon effect
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The presence of a silicon group reverses the relative reactivity of carbonate and acetate in palladium-catalyzed nucleophilic substitutions.
- Thorimbert, Serge,Malacria, Max
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- Copper-Catalyzed Dehydrogenative Diels-Alder Reaction
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A practical and effective copper-catalyzed dehydrogenative Diels-Alder reaction of gem-diesters and ketone with dienes has been established. The active dienophiles were generated in situ via a radical-based dehydrogenation process, which reacted with a wide variety of dienes to afford various polysubstituted cyclohexene derivatives in good to excellent yields.
- Jiang, Bing,Liang, Qiu-Ju,Han, Yu,Zhao, Meng,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 3215 - 3219
(2018/06/11)
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- Palladium-catalyzed [4 + 2] cycloaddition of aldimines and 1,4-dipolar equivalents via amphiphilic allylation
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The combination of Pd catalyst and diethylzinc with triethylborane promotes the amphiphilic allylation of aldimines with 2,3-bismethylenebutane-1,4-diol derivatives to serve as bis-allylic zwitterion species to form 3,4-bismethylenepiperidines via a formal [4 + 2] cycloaddition reaction. 3,4-Bismethylenepiperidine rings are applicable for the synthesis of isoquinoline derivatives via the Diels-Alder reaction followed by an oxidation reaction with DDQ.
- Hirata, Goki,Yamada, Naoshi,Sanada, Shohei,Onodera, Gen,Kimura, Masanari
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supporting information
p. 600 - 603
(2015/03/04)
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- Efficient acetylation of alcohols and phenols catalyzed by recyclable lithium bis(perfluoroalkylsulfonyl)imide
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An efficient acetylation of alcohols and phenols catalyzed by lithium bis(perfluoroalkylsulfonyl)-imide was developed. This acetylation features good yields, mild reaction condtions, and simple workup procedures. Furthermore, the catalyst bearing a long perfluoroalkyl chain is recoverable and readily reusable without losing any activity. Copyright
- Li, Guilong,Zhao, Gang
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p. 34 - 43,10
(2020/08/24)
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- A green method for selective acetylation of primary alcohols using ethyl acetate and solid potassium carbonate
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A simple and selective acetylation of primary alcohols in the presence of other reactive functionalities such as secondary alcohol, phenol, acetonide and amine is described using mild ethyl acetate as the acetyl-transfer agent and solid potassium carbonate as the catalyst.
- Mallesha,Rao, S. Prahlada,Suhas,Gowda, D. Channe
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experimental part
p. 536 - 539
(2011/11/30)
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- Synthesis and monoamine uptake inhibition of conformationally constrained 2β-carbomethoxy-3β-phenyl tropanes
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A series of 2β-carbomethoxy-3β-phenyl tropanes with conformationally constrained nitrogen substituents were synthesized as potential selective dopamine transporter ligands. These novel compounds were examined for their monoamine uptake inhibition potency at the human dopamine transporter (hDAT), the human serotonin transporter (hSERT) and the human noradrenalin transporter (hNET), stably expressed in human embryonic kidney cells (HEK). A SAR-study was conducted to determine the contribution of extended, 4-fluorinated, conformationally constrained C4 chains at the tropane nitrogen to human monoamine transporter affinity and selectivity. The Royal Society of Chemistry 2009.
- Riss, Patrick Johannes,Hummerich, Rene,Schloss, Patrick
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experimental part
p. 2688 - 2698
(2009/09/07)
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- Asymmetric synthesis of 2-aryl-5-oxotetrahydrofuran-2-carboxylic acids
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3-Aryl-2-hydroxycyclopent-2-en-1-ones, when subjected to asymmetric oxidation, result in enantiomerically enriched 2-aryl-5-oxotetrahydrofuran-2- carboxylic acids. Electron-donating substituents in the para position of the phenyl ring increase the yield and decrease the enantioselectivity of the process. Georg Thieme Verlag Stuttgart.
- Jogi, Artur,Paju, Anne,Pehk, Tonis,Kailas, Tiiu,Mueuerisepp, Aleksander-Mati,Kanger, Tonis,Lopp, Margus
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p. 3031 - 3036
(2008/02/08)
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- Acetonyltriphenylphosphonium bromide (ATPB): A versatile reagent for the acylation of alcohols, phenols, thiols and amines and for 1,1-diacylation of aldehydes under solvent-free conditions
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A wide variety of alcohols, phenols, amines and thiols may easily be converted into the corresponding acetate derivatives by treatment with acetic anhydride (1.5-2.0 equivalents) in the presence of acetonyltriphenylphosphonium bromide (ATPB; 5 mol %) in good yields at room temperature. With the same precatalyst, both aliphatic and aromatic aldehydes can also be transformed into the corresponding gemdiacetates under reflux conditions.
- Khan, Abu T.,Choudhury, Lokman H.,Ghosh, Subrata
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p. 2782 - 2787
(2007/10/03)
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- Thermal pericyclic tandem reactions
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Gas phase thermal isomerizations of twelve acetylenic systems, all of which can in principle undergo two successive pericyclic steps, are described. The substrates, the syntheses and spectroscopic properties of which are presented, are formal derivatives of but-2-yne, with different functional groups in the 1- and the 4-positions. The Cope, Claisen, Claisen ester, retro-ene, 1,5-hydrogen shift, and 1,5-homo hydrogen-shift processes were employed as the pericyclic steps from which the tandem processes were composed. The compositions of the pyrolysates obtained were determined over broad temperature ranges, and the mechanisms of the individual steps producing the pyrolysis products are discussed.
- Hopf, Henning,Wolff, Joachim
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p. 4009 - 4030
(2007/10/03)
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- Carbon-halogen bond activation by Nickel catalyst: Synthesis of alkenes, from 1,2-dihalides
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Unsaturated hydrocarbons can easily be prepared in a few seconds starting from 1,2 dibromides in the presence of a catalytic amount of Nickel diphenylphosphinoethane dichloride (NidppeCl2) and tri.n.butyl tin hydride, (TBTH) at room temperature. The dependencie of the nature of starting dihalides is investigated.
- Malanga, Corrado,Mannucci, Serena,Lardicci, Luciano
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p. 1021 - 1028
(2007/10/03)
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- Highly Selective Monoacylation of Symmetric Diols Catalyzed by Metal Sulfates Supported on Silica Gel
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Several 1,α-diols, ranging from 1,2-ethanediol to 1,16-hexadecanediol, were monoacylated with high selectivity by reaction with esters in the presence of metal sulfates or hydrogen sulfates, like Ce(SO4)2 and NaHSO4, supported on silica gel.Symmetrical secondary diols were also selectively monoformylated, by reaction with ethyl formate.This method of selective esterification is simple and practical.The yield of monoester depends upon both the composition and the volume of the solvent (an ester/alkane mixture).Unsupported NaHSO4 also catalyzed monoacylation, but the selectivity was less than in monoacylations catalyzed by the supported reagent.The selectivity can be explained by the following reasons: (1) monoacylated products are formed selectively because the diol, but not the monoester, is preferentially adsorbed on the surface of the catalysts, where esterification then occurs, and (2) thin diol layers are formed on the surface of the catalysts due to limited solubility of the diols in the solvent.
- Nishiguchi, Takeshi,Kawamine, Katsumi,Ohtsuka, Tomoko
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p. 312 - 316
(2007/10/02)
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- STEREOCHEMISTRY OF THE HOMOLYTIC HETEROCYCLIZATION OF ALKYNES WITH 1,2-ETHANEDITHIOL INTO 1,4-DITHIANES
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The homolytic heterocyclization of dialkyl-, and diaryl-acetylenes with 1,2-ethanedithiol leads stereoselectively to cis-2,3-disubstituted 1,4-dithianes.The stereochemistry of the reactions is determined by a combination of homolytic trans addition at the triple bond and intramolecular homolytic cis addition at the double bond.The main product of the heterocyclization of dimethyl acetylenedicarboxylate is dimethyl 5,6-dihydro-1,4-dithiin-2,3-dicarboxylate.
- Troyanskii, E. I.,Strelenko, Yu. A.,Demchuk, D. V.,Samoshin, V. V.,Lutsenko, A. I.,Nikishin, G. I.
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p. 1629 - 1636
(2007/10/02)
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- SYNTHESIS OF 1-ACETOXY-2-ALKYL-2,3-BUTADIENES AND/OR 2,3-DIALKYL-1,3-BUTADIENES FROM 1,4-DIACETOXY-2-BUTYNE AND ALKYL HETEROCUPRATES
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The reaction between 1,4-diacetoxy-2-butyne (5) and organocopper species of general formula RCu*MgBrCl*LiBr (4) leads to 2-alkyl-2,3-butadien-1-yl acetates 6 and/or to 2,3-dialkyl-1,3-butadienes 7 depending on the 4/5 molar ratios used.Dienes 7 can be prepared in rather good yields by reaction of 5 with a large molar excess of 4 at -70 deg C.On the other hand, unsymmetrically substituted 2,3-dialkyl-1,3-butadienes (e.g. 4,4-dimethylenedecane, 10) can be synthesized in good yields by reacting 6 with 2 equivalents of 4.The reactions which afford symmetrically or unsymmetrically substituted 2,3-dialkyl-1,3-butadienes give rise also to the formation of 2-alkyl-1,3-butadienes.A mechanism which explains the formation of mono- or di-substituted 1,3-butadienes in the above-mentioned reactions is proposed.
- Carpita, Adriano,Benetti, Massimo,Rossi, Renzo
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p. 415 - 420
(2007/10/02)
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