- Oxidative Dearomatization of 4,5,6,7-Tetrahydro-1H-indoles Obtained by Metal- and Solvent-Free Thermal 5-endo-dig Cyclization: The Route to Erythrina and Lycorine Alkaloids
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A facile one-pot approach based on a thermally induced metal- and solvent-free 5-endo-dig cyclization reaction of the amino propargylic alcohols in combination with Dess-Martin periodinane-promoted oxidative dearomatization of 4,5,6,7-tetrahydroindole intermediates provides an efficient and robust access to 5,6-dihydro-1H-indol-2(4H)ones. Green, relatively mild and operationally simple characteristics of the synthetic sequence are the major advantages, which greatly amplify the developed methodology. The utility of obtained indolones as unified key precursors is demonstrated by the application of these products to the formal total syntheses of a whole pleiad of Erythrina- and Lycorine-type alkaloids, namely (±)-erysotramidine, (±)-erysotrine, (±)-erythravine, (±)-γ-lycorane, and abnormal erythrinanes (±)-coccoline and (±)-coccuvinine.
- Andreev, Ivan A.,Ratmanova, Nina K.,Novoselov, Anton M.,Belov, Dmitry S.,Seregina, Irina F.,Kurkin, Alexander V.
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p. 7262 - 7267
(2016/05/19)
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- Multicomponent reactions in PEG-400: Ruthenium-catalyzed synthesis of substituted pyrroles
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An efficient and eco-friendly method for the synthesis of substituted pyrroles has been developed via ruthenium-catalyzed multicomponent reaction of ketone, amine, and ethylene glycol in PEG-400 as solvent medium without using any external ligand. The cat
- Chandrasekhar, Srivari,Patro, Vidyavathi,Chavan, Lahu N.,Chegondi, Rambabu,Grée, René
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supporting information
p. 5932 - 5935
(2015/01/08)
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- Solvent free selective dehydrogenation of indolic and carbazolic molecules with an iridium pincer catalyst
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A previously known iridium POCOP pincer catalyst was found to selectively dehydrogenate the heterocyclic portion of several indolic and carbazolic molecules. These molecules were found to have an "activity window" (172-178 °C) upon which only the heterocyclic ring underwent dehydrogenation. All reactions were run solvent free, yields for selected substrates were excellent, and the products were isolated by either distillation or alumina plug filtration. the Partner Organisations 2014.
- Brayton, Daniel F.,Jensen, Craig M.
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p. 5987 - 5989
(2014/05/20)
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- Synthesis of 4,5,6,7-tetrahydro-1H-indole derivatives through successive sonogashira coupling/Pd-mediated 5-endo-dig cyclization
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A one-pot Sonogashira cross-coupling/5-endo-dig cyclization procedure leading to 2-aryl-4,5,6,7-tetrahydroindoles was developed. This short (only two steps from commercially available compounds) sequence avoids harsh conditions and expensive catalysts. Our procedure is highly tolerant to a range of functional groups (amino, nitro, carboxy, cyano, hydroxy, and bromo). A family of 21 tetrahydroindoles was synthesized on a gram scale in a good to excellent yields, which is indicative of the general character and scalability of this reaction. This methodology allows access to indoles bearing miscellaneous substituents at the C2 position (by variation of ArI) and at the nitrogen atom (by variation of RNH2, including chiral moieties). A one-pot sequence based on Sonogashira cross-coupling/Pd-mediated 5-endo-dig cyclization was developed and applied to the gram-scale synthesis of 2-aryl-4,5,6,7- tetrahydroindoles (21 examples). Copyright
- Andreev, Ivan A.,Belov, Dmitry S.,Kurkin, Alexander V.,Yurovskaya, Marina A.
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p. 649 - 652
(2013/03/13)
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- OXAZOLIDINES. 1. BASIC CATALYTIC DISPROPORTIONATION OF CYCLOHEXANOSPIRO-2-OXAZOLIDINES: SYNTHESIS OF N-SUBSTITUTED 4,5,6,7-TETRAHYDROINDOLES
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It has been shown that the basic catalytic disproportionation of cyclohexanospiro-2-oxazolidines in the presence of potasium hydroxide or sodium methylate leads to N-substituted 4,5,6,7-tetrahydroindoles with a yield of up to 73percent.The influence of the character of substituents at the nitrogen atom of oxazolidine on the course of the reaction has been established.
- Kukharev, B.F.,Stankevich, V.K.,Kukhareva, V.A.
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p. 437 - 439
(2007/10/02)
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- Pyrrole Annulation onto Aldehydes and Ketones via Palladium-Catalyzed Reactions
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α-Dicarbonyl systems reacted with vinylmagnesium bromide and acetic anhydride to give α-acetoxy-α-vinylalkanones.These substrates react with benzylamine in the presence of tetrakis(triphenylphosphine)palladium to give N-benzylpyrroles with substituents in the two and/or three position.The functiodifferentiated synthesis of α-dicarbonyl compounds from ketones makes this a pyrrole annulation onto any α-methylene carbonyl system.
- Trost, Barry M.,Keinan, Ehud
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p. 2741 - 2746
(2007/10/02)
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