103166-34-3Relevant academic research and scientific papers
Catalytic multicomponent synthesis of highly substituted pyrroles utilizing a one-pot sila-stetter/paal-knorr strategy
Bharadwaj, Ashwin R.,Scheidt, Karl A.
, p. 2465 - 2468 (2004)
(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.
Hexafluoroisopropanol as solvent and promotor in the Paal-Knorr synthesis of N-substituted diaryl pyrroles
Schirmacher, Robert H.E.,R?sch, Daniel,Thomas, Franziska
, (2021/02/20)
An additive-free synthesis of challenging N-substituted aryl pyrroles from the often poorly soluble corresponding 1,4-diketones by means of the Paal-Knorr pyrrole synthesis is reported, which makes use of the unique properties of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a solvent and reaction promotor. Our procedure offers simple execution and purification as well as easy scale-up and can be applied in the Paal-Knorr synthesis of a large number of structurally diverse pyrroles including the synthetically challenging tetra- and penta-substituted pyrroles in moderate to excellent yields. HFIP can also be used as solvent in the Paal-Knorr synthesis of furans and thiophenes; however, the solvent effect is more pronounced in synthesis of pyrroles.
Boehmite nanoparticles, an efficient green catalyst for the multi-component synthesis of highly substituted imidazoles
Keivanloo, Ali,Bakherad, Mohammad,Imanifar, Elahe,Mirzaee, Mahdi
, p. 291 - 300 (2013/09/02)
Boehmite nanoparticles (AlOOH NPs) was found to be a highly active and green catalyst for the synthesis of highly substituted imidazoles under solvent-free conditions. This one-pot procedure is very simple, and affords good to excellent yields. Furthermore, the catalyst shows good thermal stability and recyclability. The catalyst was recycled for five runs without an appreciable loss in its catalytic activity.
Thiazolium-catalyzed additions of acylsilanes: A general strategy for acyl anion addition reactions
Mattson, Anita E.,Bharadwaj, Ashwin R.,Zuhl, Andrea M.,Scheidt, Karl A.
, p. 5715 - 5724 (2007/10/03)
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.
The Reactions of Monoalkylthio- or Monoarylthio-Substituted Cyclopropenium Salt with Nitrogen Nucleophiles: Formation of Polyfunctionally Substituted Pyrroles or Pyrazoles
Yoshida, Hiroshi,Utsumi, Fumitaka,Suzuki, Hideki,Ito, Satoru,Sakashita, Shin-ichi,et al
, p. 698 - 702 (2007/10/02)
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
Electron transfer reactions. Reaction of nitrogen heterocycles with potassium
Muneer, Mohammed,Kamat, Prashant V.,George, Manapurathu V.
, p. 969 - 975 (2007/10/02)
The results of our studies on potassium-induced transformations of some selected nitrogen heterocycles are presented.The substrates under investigation include 2,3-diphenylindole (1a), 2,3-diphenyl-1-methylindole (1b), 1,2,3-triphenylindole (1c), 2,3,4,5-tetraphenylpyrrole (5a), 1,2,3,5-tetraphenylpyrrole (5b), 1-benzyl-2,3,5-triphenylpyrrole (5c), 2,4,5-triphenyloxazole (15a), 4,5-diphenyl-2-methyloxazole (15b), 2,4-diphenyl-5-methyloxazole (15c), and 2,4,5-triphenylimidazole (19).Treatment of 1a with potassium in THF gave 9H-dibenzocarbazole (3a), whereas 1c gave a mixture of 9-phenyl-9H-dibenzocarbazole (3c) and 2,3-diphenylindole (1a).Under identical conditions, 1b gave only the cleavage product 1a.In contrast, when the reactions of 1a,c were carried out with potassium in THF saturated with oxygen, and with potassium superoxide in benzene containing 18-crown-6, a mixture of 2-benzamidobenzophenone (4a), the carbazoles 3a,c, and 1a was formed.Although no product was isolated on treatment of 5a with potassium in THF, the reaction of 5a with potassium in THF saturated with oxygen gave a mixture of tetraphenylpyrazine (7a), the benzoylaminostilbene 8a, the lactam 12a, benzamide (11a), and benzoic acid (14).Similar results were obtained in the reaction of 5a with potassium superoxide.The reaction of N-substituted pyrroles such as 5b,c with potassium gave the NH pyrrole 9b in each case, whereas the reaction of 5b,c with potassium in THF, saturated with oxygen, gave a mixture of 9b, the butanone 10b, the 1,4-dione 13b, the lactam 12b, the amides 11a-c, and benzoic acid (14).Attempted reactions of 5b,c with potassium superoxide did not give any isolable product; most of the starting material could be recovered unchanged in each case.A mixture of N-(1,2-diphenylethyl)benzamide (18a) and benzoic acid (14) was formed in the reaction of the oxazole 15a with potassium, whereas 15b,c, under analogous conditions, gave the N-vinylamides 17b,c and benzoic acid (14).In contrast, treatment of the imidazole 19 with potassium in THF did not give any product; however, when the reaction of 19 was carried out with potassium in THF saturated with oxygen, and with potassium superoxide, dibenzamide (21) was isolated, in each case.Radical ions have been invoked as intermediates in the transformation of the different substrates to the observed products.Cyclic voltammetric studies have been carried out to measure the reduction potentials of these radical anion intermediates.These radical anions have also been generated by pulse radiolysis in methanol, and their absorption spectra recorded.
