109-97-7Relevant articles and documents
1-pyrrole from Trimethyl(1-pyrrolyl)ammonium Ion
Zeltner, Peter,Bernauer, Karl
, p. 1860 - 1864 (1983)
Trimethyl(1-pyrrolyl)ammonium iodide (5a) and the corresponding p-toluenesulfonate 5b are transformed by strong bases into 1-pyrrole (9), i.e. into a N-Mannich base, a type of compound novel in the pyrrole series.In this reaction, which is very fast in DMSO the cation of compounds 5 is deprotonated to form the nitrogen ylide 6.The latter undergoes a Stevens-type rearrangement to 9.Several facts, namely the negative outcome of a cross-reaction experiment with 3,4-dimethylpyrrole and of an attempt to obtain 9 from pyrrole and dimethyl(methylidene)ammonium iodide in the presence of one equivalent of sodium methoxide, as well as unsuccessful CIDNP studies point to a rearrangement mechanism via the contact ion pair 12.
Devinylation of N-vinylpyrroles using mercury(II) acetate
Schmidt,Vasil'Tsov,Zorina,Ivanov,Mikhaleva,Trofimov
, p. 1300 - 1303 (2012)
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Haitinger
, p. 228 (1882)
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Tsukamoto,Lichtin
, p. 3798 (1960)
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Whitten et al.
, p. 322 (1966)
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Flash flow pyrolysis: Mimicking flash vacuum pyrolysis in a high-temperature/high-pressure liquid-phase microreactor environment
Cantillo, David,Sheibani, Hassan,Kappe, C. Oliver
, p. 2463 - 2473 (2012)
Flash vacuum pyrolysis (FVP) is a gas-phase continuous-flow technique where a substrate is sublimed through a hot quartz tube under high vacuum at temperatures of 400-1100 °C. Thermal activation occurs mainly by molecule-wall collisions with contact times in the region of milliseconds. As a preparative method, FVP is used mainly to induce intramolecular high-temperature transformations leading to products that cannot easily be obtained by other methods. It is demonstrated herein that liquid-phase high-temperature/high- pressure (high-T/p) microreactor conditions (160-350 °C, 90-180 bar) employing near- or supercritical fluids as reaction media can mimic the results obtained using preparative gas-phase FVP protocols. The high-T/p liquid-phase "flash flow pyrolysis" (FFP) technique was applied to the thermolysis of Meldrum's acid derivatives, pyrrole-2,3-diones, and pyrrole-2-carboxylic esters, producing the expected target heterocycles in high yields with residence times between 10 s and 10 min. The exact control over flow rate (and thus residence time) using the liquid-phase FFP method allows a tuning of reaction selectivities not easily achievable using FVP. Since the solution-phase FFP method does not require the substrate to be volatile any more -a major limitation in classical FVP-the transformations become readily scalable, allowing higher productivities and space-time yields compared with gas-phase protocols. Differential scanning calorimetry measurements and extensive DFT calculations provided essential information on pyrolysis energy barriers and the involved reaction mechanisms. A correlation between computed activation energies and experimental gas-phase FVP (molecule-wall collisions) and liquid-phase FFP (molecule-molecule collisions) pyrolysis temperatures was derived.
Chlorination of Pyrrole. N-Chloropyrrole: Formation and Rearrangement to 2- and 3-Chloropyrrole
Rosa, Michael De
, p. 1008 - 1010 (1982)
N-Chloropyrrole (2) was formed in 65-72percent yield when pyrrole (1) in CCl4 was chlorinated with aqueous NaOCl.This intermediate rearranged in methanol to give chloropyrroles by two distinct reactions: a thermal rearrangement which gave 2-chloropyrrole (3) and an acid-catalyzed intermolecular reaction which gave 2-chloropyrrole (3), 3-chloropyrrole (4), and 2,5-dichloropyrrole (5).Nucleophilic attack on the N-Cl bond of 2 was demonstrated by reactions in the presence of CN- and SCN-.In the latter case, 2-(thiocyano)pyrrole was formed.
Kinetics of elimination of several heterocyclic carbamates in the gas phase
Brusco, Yannely,Dominguez, Rosa M.,Rotinov, Alexandra,Herize, Armando,Cordova, Mary,Chuchani, Gabriel
, p. 796 - 800 (2002)
The kinetics of the gas-phase elimination of several heterocyctic carbamates were determined in a static system over the temperature range 190.0-409.7°C and the pressure range 26.5-125 Torr (1 Torr = 133.3 Pa). The reactions in seasoned vessels, with the free radical inhibitor cyciohexene and/or toluene always present, are homogeneous and unimolecular and obey a first-order rate law. The observed rate coefficients are represented by the following Arrhenius equations: for tert-butyl-1-pyrrolidine carboxylate, log k1 (s-1) = (11.36 ± 0.31) - (145.4 ± 3.1) kJ mol-1 (2.303RT)-1; for 1-(tert-butoxycarbonyl)-2-pyrrolidinone, log k1 (s-1) = (11.54 ± 0.29) - (140.8 ± 2.8) kJ mol-1 (2.303RT)-1; for tert-butyl-1-pyrrole carboxylate, log k1 (s-1): (12.12 ± 0.05) - (145.2 ± 1.0) kJ mol-1 (2.303RT)-1; and for 1-ethylpiperazine carboxylate, log k1 (s-1): (12.05 ± 0.19) - (188.2 ± 4.6) kJ mol-1 (2.303RT)-1 The saturated heterocyclic carbamates show a decrease in rates of elimination due to electronic factors. Heterocyclic carbamates with a nitrogen atom able to delocalize its electrons with π-bonds present in the ring were found to enhance the rates due to resonance interactions. Copyright
Decarboxylation via addition of water to a carboxyl group: Acid catalysis of pyrrole-2-carboxylic acid
Mundle, Scott O. C.,Kluger, Ronald
, p. 11674 - 11675 (2009)
(Chemical Equation Presented) The decarboxylation of pyrrole-2-carboxylic acid is subject to acid catalysis in strongly acidic solutions. Protonation of the pyrrole ring at C2 produces a potentially low-energy carbanion leaving group. Carbon dioxide forma
Sulfoxylate Anion Radical-Induced Aryl Radical Generation and Intramolecular Arylation for the Synthesis of Biarylsultams
Gupta, Pankaj,Laha, Joydev K.
supporting information, (2022/03/16)
Aryl radical generation from the corresponding aryl halides using an electron donor and subsequent intramolecular cyclization with arenes could be an important advancement in contemporary biaryl synthesis. A green and practically useful synthetic protocol to access diverse six- and seven-membered biarylsultams especially with a free NH group including demonstration of a gram-scale synthesis is reported herein. The sulfoxylate anion radical (SO2-?), generated in situ from the reagents rongalite or sodium dithionite (Na2S2O4), was found to be the key single electron transfer agent forming aryl radicals from aryl halides, which upon intramolecular arylation gives biarylsultams with good to excellent yields. The approach features generation of aryl radicals that remained underexplored, use of a cheap and readily available industrial reagents, and transition metal-free, mild, and green reaction conditions.
Rearrangement and cyclisation reactions on the 1-Arylpyrrol-2-iminyl-2-Aryliminopyrrol-1-yl radical energy surface
Borthwick, Scott,Foot, Jonathan,Ieva, Maria,McNab, Hamish,McNab, Lilian,Rozgowska, Emma J.,Wright, Andrew
supporting information, p. 161 - 175 (2021/02/02)
Independent generation of the iminyl (X = N) and pyrrol-1-yl (X = N) radicals by flash vacuum pyrolysis of the corresponding oxime ether and N-(dimethylamino) compound, respectively, provides two regioisomeric pyrrolo1,2-A]quinoxalines compounds. This shows that the radical species interconvert via the spirodienyl moeity at high temperatures. Corresponding generation of the pyrrol-1-yl (X = CH) radical gives the pyrrolo[1,2-A]quinoline as the only cyclised product. In this case, DFT calculations suggest that direct cyclisation of the pyrrol-1-yl takes place, rather than formation of the spirodienyl species and exclusive migration of the C-N bond.
