- One pot regiospecific synthesis of polysubstituted pyrroles from benzylamines and ynones under metal free conditions
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A convenient one-pot weak base-promoted synthesis of polysubstituted pyrroles has been developed from benzylamines and ynones. This transformation involves the Michael addition reaction and intramolecular condensation, which features high regioselectivity, high efficiency, environmental friendliness and metal free. A series of polysubstituted pyrroles were provided in up to 91% yield for 27 examples.
- Shen, Jinhai,Cheng, Guolin,Cui, Xiuling
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supporting information
p. 10641 - 10643
(2013/11/06)
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- Thiazolium-catalyzed additions of acylsilanes: A general strategy for acyl anion addition reactions
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A strategy utilizing N-heterocyclic carbenes (NHCs) derived from thiazolium salts has been developed for the generation of carbonyl anions from acylsilanes. Synthetically useful 1,4-diketones and N-phosphinoyl-α- aminoketones have been prepared in good to excellent yields via NHC-catalyzed additions of acylsilanes to the corresponding α,β-unsaturated systems and N-phosphinoylimines. These organocatalytic reactions are air- and water-tolerant methods to execute robust carbonyl anion addition reactions. Additionally, polysubstituted aromatic furans and pyrroles have been efficiently synthesized in a one-pot process using this carbonyl anion methodology. The addition of alcohols to the reaction renders the process catalytic in thiazolium salt. In an effort to synthesize a potential intermediate along the proposed reaction pathway, silylated thiazolium carbinols have been identified to provide good yields of carbonyl anion addition products when subjected to the standard reaction conditions in the presence of suitable electrophiles.
- Mattson, Anita E.,Bharadwaj, Ashwin R.,Zuhl, Andrea M.,Scheidt, Karl A.
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p. 5715 - 5724
(2007/10/03)
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- Synthesis of pyrroles from 1-dialkylamino-3-phosphoryl(or phosphanyl)allenes through 1,5-cyclization of conjugated azomethine ylide intermediates
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1-Dialkylamino-1,3-diaryl-3-diphenylphosphanylallenes 3a-e are thermally converted into a-annulated 3,5-diarylpyrroles 6a-f and [a]-annulated benzo[c]azepines 7a,b,d. These transformations are likely to include conjugated azomethine ylide intermediates that can undergo either a 1,5- or a 1,7-electrocyclization. The periselectivity is markedly shifted toward 1,5-cyclization when the diphenylphosphanyl substituent is replaced by the diphenylphosphoryl group. Thus, 1-dialkyl-amino-3-(diphenylphosphoryl)allenes 4a-f yield pyrroles 6 exclusively and with improved yields, unless the 3-aryl substituent in the allene is too electron-rich (e.g., benzodioxol-5-yl, 4f → 7f). The preparation and thermal transformation of aminoallenes 4 over three or four steps can be conducted as a one-pot procedure, thus providing a convenient synthesis of [a]-annulated 3,5-diarylpyrroles from enaminoketones.
- Reisser, Martin,Maas, Gerhard
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p. 4913 - 4924
(2007/10/03)
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- Catalytic multicomponent synthesis of highly substituted pyrroles utilizing a one-pot sila-stetter/paal-knorr strategy
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(Equation Presented) A multicomponent synthesis of highly substituted pyrroles catalyzed by thiazolium salts has been disclosed. The reaction employs an acyl anion conjugate addition reaction of acylsilanes (sila-Stetter) and unsaturated ketones to generate 1,4-dicarbonyl compounds in situ. The subsequent addition of various amines promotes a Paal-Knorr reaction, affording the desired pyrrole nucleus in an efficient one-pot process.
- Bharadwaj, Ashwin R.,Scheidt, Karl A.
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p. 2465 - 2468
(2007/10/03)
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- The Reactions of Monoalkylthio- or Monoarylthio-Substituted Cyclopropenium Salt with Nitrogen Nucleophiles: Formation of Polyfunctionally Substituted Pyrroles or Pyrazoles
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The reactions of monoalkylthio- or monoarylthio-substituted cyclopropenium salt (1) with a number of secondary amines were studied.The amines, such as N-methylaniline, yielded indenes, whereas N-alkyl- or N-arylbenzylamines gave 1-alkyl or 1-aryl-2-phenyl
- Yoshida, Hiroshi,Utsumi, Fumitaka,Suzuki, Hideki,Ito, Satoru,Sakashita, Shin-ichi,et al
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p. 698 - 702
(2007/10/02)
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- Reaction of Anions from Monoimines of Benzil with Alkylating Agents. Photochemical Reactivity of Some 4-Alkoxy-2-aza-1,3-dienes
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The reaction of benzil benzhydrylmonoimine 6a with methyl iodide or dimethyl sulphate as the electrophile affords 4-alkoxy-2-aza-1,3-dienes resulting from an O-alkylation.When benzyl chloride is employed, products of O-alkylation C-alkylation and cyclization are produced, while with toluene-p-sulphonyl chloride only cyclization to a dihydro-oxazole takes place.Benzil α-phenylethylmonoimine 6b yields only products of C- and/or O-alkylation.In one case, when a large excess of dimethyl sulphate is used, cyclization affords N-methyl-2,3,5-triphenylpyrrole.Irradiation of the O-alkylated compounds (E)- and (Z)-4-methoxy-1,1,3,4-tetraphenyl-2-azabuta-1,3-diene and (E)-4-benzyloxy-1,1,3,4-tetraphenyl-2-azabuta-1,3-dienes in the presence of perchloric acid yields isoquinoline derivatives by a photo-Mannich reaction.
- Armesto, Diego,Horspool, William M.,Ortiz, Maria J.,Romano, Santiago
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p. 171 - 176
(2007/10/02)
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- OXIDATION OF 1,2,3,4,6,-SUBSTITUTED PYRIDINIUM SALTS WITH FERRICYANIDE
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Quaternary pyridiniun salts IIa-IId are oxidized with alkaline solution of potassium ferricyanide to give a mixture of pyrrole derivatives Ia-Ib and IVa-IVd.The quaternary salt IIeunder the same conditions affords a mixture of compouns IVe and V vhereas I
- Nesvadba, Petr,Kuthan, Josef
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p. 543 - 548
(2007/10/02)
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