- Organocatalytic [10+4] cycloadditions for the synthesis of functionalised benzo[a]azulenes
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A direct and mild strategy for the synthesis of benzo[a]azulenes based on an organocatalytic [10+4] cycloaddition reaction is described. The strategy enables a diversity-oriented approach for the synthesis of various poly-functionalised azulenes from easily accessible starting materials.
- Giardinetti, Maxime,Jessen, Nicolaj Inunnguaq,Christensen, Mette Louise,J?rgensen, Karl Anker
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supporting information
p. 202 - 205
(2019/01/04)
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- Selective cyclodimerization and cyclotrimerization of acetals bearing electron-withdrawing groups catalyzed by lewis acids
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Acetais like 3,3-dlethoxyproplonate bearing electron-withdrawing groups were found to undergo cyclodimerization and cyclotrimerization in the presence of Lewis acids to give coumalates and 1,3,5-trisubstituted benzenes. The selectivity of these products depended on the Lewis acids employed. For instance, ethyl coumalate was obtained from, ethyl 3,3diethoxypropionate in high selectivity under the influence of d-block Lewis acids like FeCl3, whereas triethyl 1,3,5-benzenetricarboxylate was obtained in preference to ethyl coumalate under the influence of lanthanoid Lewis acids like GdCl3, Various coumalates were synthesized by the FeCl3catalyzed cross-cyclodimerization of acetals with active methylene compounds, From 4,4-diniethoxy-2-butanone, however, 1,3,5-triacetylbenzene, which is difficult to prepare regioselectively by conventional methods, was formed in quantitative yield under the influence of AlCl3, This reaction would provide a very convenient route to 1,3,5-triacetylbenzene,
- Maeda, Sayuki,Obora, Yasushi,Ishii, Yasutaka
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experimental part
p. 4067 - 4072
(2009/12/24)
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- A novel and concise synthesis of (±) 2-epi-Validamine
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(±) 2-epi-Validamine has been synthesized in five steps by the chemical manipulation of the bicyclic lactone cycloadduct of ethyl coumalate and vinylene carbonate.
- Afarinkia, Kamyar,Mahmood, Farzana
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p. 3129 - 3140
(2007/10/03)
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- Synthesis of 2-Oxo-2H-pyran-5-carboxylate Derivatives
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3-Substituted diethyl pent-2-enedioates are easily formylated by means of ethyl formate/TiCl4/4-methylmorpholine to produce the ethoxymethylene derivatives, which are smoothly cyclized either with HCOOH or PPA to the corresponding 2-oxo-2H-pyran-5-carboxylate derivatives.
- Kvita, Vratislav
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p. 411 - 416
(2007/10/02)
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- Reactions of Carboxylic Acids with "Phosphonium Anhydrides"
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General considerations are outlined for a reagent to extract oxygen from organic molecules by an equivalent of dehydration.Reagents, (R3P+)2O, 2OTf-, were created for the purpose and subjected to a preliminary study.They were found to convert carboxylic acids readily and rapidly to anhydrides, esters, amides, amidines, benzimidazoles, and cyclic aryl ketones in good yields.
- Hendrickson, James B.,Hussoin, Md. Sajjat
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p. 1144 - 1149
(2007/10/02)
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- Ketene Chemistry I. 3,3-Dialkoxypropionates and 3-Alkoxyacrylates. Acid catalysed Self-condensation of Ethyl 3,3-Diethoxypropionate and Ethyl 3-Ethoxyacrylate.
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The acid catalyzed selfcondensation of ethyl 3,3-diethoxypropionate and ethyl 3-ethoxyacrylate has been studied under various conditions.The products of the reaction include di- and trimeric, open chain structures as well as pyrones and triethyl 1,3,5-benzenetricarboxylate.
- Jacobsen, Niels,Winckelmann, Ib
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p. 987 - 996
(2007/10/02)
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