930-87-0Relevant academic research and scientific papers
Intermediates in the Paal-Knorr synthesis of pyrroles. 4-Oxoaldehydes
Amarnath,Amarnath,Valentine,Eng,Graham
, p. 234 - 238 (1995)
The mechanism of pyrrole formation between a 4-ketoaldehyde, such as 4- oxohexanal (4), and a primary amine is examined. In organic solvents 4 readily formed the imine 6 that decomposed to pyrrole 9. In phosphate buffer (pH 7.4) the presence of deuteriums in the dideuterio (4-d2) and hexadeuterio (4-d6) analogs retarded the reaction rate by factors of 1.9 and 2.6, which are much less than the isotope effects exhibited by reactions involving cleavage of the carbon-hydrogen bond. Moreover, the deuterium labels from the uncyclized ketoaldehyde remained intact. These results suggest that the hemiaminal 5 rather than the enamine 8 is the intermediate undergoing cyclization. Due to the absence of a methyl substituent at one of the carbonyls the rate of pyrrole formation of 4-oxohexanal was 2 orders of magnitude larger than that of 2,5-hexanedione. The higher rate of pyrrole formation may account for the increased rate of pyrrole-mediated cross- linking of proteins caused by γ-ketoaldehydes relative to γ-diketones.
Reaction of methylamine with acetonylacetone and its application in polymer analysis
Wang, Frank Cheng-Yu,Hasha, Dennis L.
, p. 1131 - 1137 (1999)
The reaction between methylamine and acetonylacetone is a very important one in pyrolysis polymer analysis. Polymers containing either primary amine functional groups or carbonyl functional groups separated by two methylene units can be derivatized by this reaction. The derivatized polymer undergoes a unique thermal degradation mechanism which favors qualitative and quantitative analysis by pyrolysis gas chromatography. In this study, the chromatographic and spectroscopice evidence about this reaction has been generated to verify this mechanism. The applications of this derivatization reaction in polymer analysis of (1) polyallylamine derivatized with acetonylacetone, (2) ethylene-carbon monoxide alternating copolymer derivatized with methylamine, and (3) ethylene-carbon monoxide, styrene- carbon monoxide alternating terpolymer derivatized with methylamine have been demonstrated.
Acceptorless Dehydrogenative Coupling Using Ammonia: Direct Synthesis of N-Heteroaromatics from Diols Catalyzed by Ruthenium
Daw, Prosenjit,Ben-David, Yehoshoa,Milstein, David
supporting information, p. 11931 - 11934 (2018/09/27)
The synthesis of N-heteroaromatic compounds via an acceptorless dehydrogenative coupling process involving direct use of ammonia as the nitrogen source was explored. We report the synthesis of pyrazine derivatives from 1,2-diols and the synthesis of N-substituted pyrroles by a multicomponent dehydrogenative coupling of 1,4-diols and primary alcohols with ammonia. The acridine-based Ru-pincer complex 1 is an effective catalyst for these transformations, in which the acridine backbone is converted to an anionic dearomatized PNP-pincer ligand framework.
A convenient one-pot synthesis of polysubstituted pyrroles from N-protected succinimides
Kobeissi, Marwan,Yazbeck, Ogaritte,Chreim, Yamama
supporting information, p. 2523 - 2526 (2014/05/06)
The dienamine products formed by the reaction between polysubstituted succinimides and the Petasis reagent were subjected to isomerization under mild acidic conditions to give polysubstituted pyrroles in excellent yields (85-95%). The scope and limitations of this methodology are explored.
DIASTEREOSELECTIVE ELECTROCHEMICAL REDUCTIVE AMINATION OF 2,5-HEXANEDIONE AND 2,6-HEPTANEDIONE
Concialini, Vittorio,Roffia, Sergio,Savoia, Diego
, p. 77 - 82 (2007/10/02)
The electrochemical reductive amination of 2,5-hexanedione with ammonia and 1-phenylethylamine at the mercury cathode afforded the corresponding 2,5-dimethylpyrrolidines with satisfactory yield and excellent cis-selectivity (90-98percent), but with arylamines mixtures of pyrroles and diastereoisomeric pyrrolidines were obtained.Only pyrroles were obtained with methyl- and benzylamine.On the other hand, 2,6-dimethylpiperidine (98percent cis) was obtained in low yield from 2,6-heptanedione and ammonia.The stereochemical outcome, along with the observation of a single reduction peak for the overall four-electron reduction, is consistent with a mechanism involving reduction of iminium ions, where the diastereoselctivity is controlled in the protonation of cyclic α-aminoalkyl radicals at the radical carbon atom.However, an alternative mechanism, involving the reduction of radicals to the corresponding carbanions followed by fast protonation, although less probable, could not be discarded.
An Electron Spin Resonance Study of the Radical Cations of Pyrroles, Furans, and Thiophenes in Liquid Solution
Davies, Alwyn G.,Julia, Luis,Yazdi, Safieh N.
, p. 239 - 244 (2007/10/02)
Photolysis of alkylpyrroles in trifluoroacetic acid containing mercury(II) trifluoroacetate, alkylfurans in trifluoroacetic acid, or alkylthiophenes in sulphuric acid, induces oxidation to the corresponding radical cations.The e.s.r. spectra show that the electronic configuration is similar in all three species, the unpaired electron occupying the φA MO in which the heteroatom lies in a nodal plane.Photolysis of 2,6-dimethyl- and 2,6-diethyl-thiophene in trifluoroacetic acid containing mercury(II) trifluoroacetate, on the other hand, gave rise to spectra with a high g value (2.0062), showing hyperfine coupling to two non-equivalent pairs of alkyl groups in an unsymmetrical dimer.
Deacylation of Pyrrole and other Aromatic Ketones
Moon, M. W.,Wade, R. A.
, p. 2663 - 2669 (2007/10/02)
Ethyl 4-acetyl-3,5-dimethyl-1H-pyrrole-2-carboxylate (1a) reacts rapidly with ethylene glycol in refluxing benzene with p-toluenesulfonic acid or perchloric acid as a catalyst to give ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate (3) in high yield (96 percent).Various 2- and 3-acylpyrroles can be efficiently deacylated by using this procedure.Other ketones which undergo deacylation include phenyl(2-phenylindol-3-yl)methanone (19), 1-(5-methyl-1-phenylpyrazol-4-yl)ethanone (20), and 2,4-dimethoxybenzophenone.Certain pyrrole ketones where the acyl group is flanked by two ring methyl groups are also cleaved under acidic conditions by using ethanedithiol.
Electrophilic Substitution in Pyrroles. Part 4. Hydrogen Exchange in Acid Solution
Alexander, Robert s.,Butler, Anthony R.
, p. 110 - 112 (2007/10/02)
Hydrogen exchange at the unsubstituted positions in 1,2,5-trimethyl- and 1,3,4-trimethyl-pyrrole in aqueous buffer has been examined.The two positions were found to be of similar reactivities.General acid catalysis was detected.No hydrogen exchange on the methyl groups of 2,3,4,5-tetramethylpyrrole, even in strong acid, was detected.The 13C n.m.r. spectrum of the tetramethylpyrrole was examined.
