109-97-7Relevant academic research and scientific papers
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.
Carbon kinetic isotope effects reveal variations in reactivity of intermediates in the formation of protonated carbonic acid
Vandersteen, Adelle A.,Mundle, Scott O. C.,Lacrampe-Couloume, Georges,Sherwood Lollar, Barbara,Kluger, Ronald
, p. 12176 - 12181 (2013)
Kinetic evidence suggests that acid-catalyzed decarboxylation reactions of aromatic carboxylic acids can occur by a hydrolytic process that generates protonated carbonic acid (PCA) as the precursor of CO2. Measurements of reaction rates and carbon kinetic isotope effects (CKIE) for decarboxylation of isomeric sets of heterocyclic carboxylic acids in acidic solutions reveal that C-C cleavage to form PCA is rate-determining with significant variation in the magnitude of the observed CKIE (1.018-1.043). Larger values are associated with the more reactive member in each isomeric pair. This variation is consistent with stepwise mechanisms in which C-C cleavage is competitive with C-O cleavage, leading to reversion to the protonated reactant to varying degrees with an invariant intrinsic CKIE for C-C cleavage. Thus, the relative barriers to reversion and formation of PCA control the magnitude of the observed CKIE in a predictable manner that correlates with reactivity. Application of the proposed overall mechanism reveals that carboxylation reactions in acidic solutions will proceed by way of initial formation of PCA.
Integrating Biomass into the Organonitrogen Chemical Supply Chain: Production of Pyrrole and d-Proline from Furfural
Di, Lu,Fung Kin Yuen, Vincent,Song, Song,Sun, Qiming,Yan, Ning,Zhou, Kang
, p. 19846 - 19850 (2020)
Production of renewable, high-value N-containing chemicals from lignocellulose will expand product diversity and increase the economic competitiveness of the biorefinery. Herein, we report a single-step conversion of furfural to pyrrole in 75 % yield as a key N-containing building block, achieved via tandem decarbonylation–amination reactions over tailor-designed Pd?S-1 and H-beta zeolite catalytic system. Pyrrole was further transformed into dl-proline in two steps following carboxylation with CO2 and hydrogenation over Rh/C catalyst. After treating with Escherichia coli, valuable d-proline was obtained in theoretically maximum yield (50 %) bearing 99 % ee. The report here establishes a route bridging commercial commodity feedstock from biomass with high-value organonitrogen chemicals through pyrrole as a hub molecule.
Unusual reactivity of N-tert-butylimines under FVT conditions
Le?niak, Stanis?aw,Pasternak, Beata,Justyna, Katarzyna,Vu, Thien Y.,Huynh, Thi Kieu Xuan,Khayar, Sa?d,Dargelos, Alain,Chrostowska, Anna
, p. 722 - 729 (2013)
Thermal reactions of N-tert-butyl-(E)-crotonaldimine (1a) and 1,4-di-(tert-butyl)-1,4-diazabuta-1,3-dien (glyoxal-bis-N-tert-butylimine) (1b) under FVT conditions have been studied. It has been found that at 800 °C compound 1a yielded pyrrole and crotonon
Reactivity of 7-Azanorbornenes in Bioorthogonal Inverse Electron-Demand Diels–Alder Reactions
Karaki, Fumika,Ohgane, Kenji,Imai, Hirotaka,Itoh, Kennosuke,Fujii, Hideaki
, p. 3815 - 3829 (2017)
In the preparation of multicomponent compounds, the accumulation of components through sequential click reactions is an attractive strategy. In this work we examined the reactivity of various N-substituted 7-azanorbornenes in inverse electron-demand Diels–Alder (iEDDA) reactions with tetrazines to explore the potential of 7-azanorbornenes as clickable hub molecules. The iEDDA reaction of 7-azanorbornene is expected to proceed faster when the nitrogen atom at the 7-position is substituted with an electron-donating substituent. Contrary to this expectation, the electron-donating alkyl-bearing derivative reacted much more slowly than those bearing electron-withdrawing acyl groups. The results of DFT calculations indicate that the reaction rates correlate well with an increase in sp2 character of the 7-nitrogen atoms: The ease of conversion of the more stable exo conformer into the more reactive endo conformer may lower the activation energy of the first rate-determining hetero-Diels–Alder step. Indeed, the reaction rates of N-acylated 7-azanorbornenes, which have a more planar nitrogen atom, were found superior to those of other derivatives and comparable to those of norbornenes. Finally, we successfully labeled a tetrazine on a protein surface by fluorophore-conjugated 7-azanorbornene in the presence of other proteins.
Acid-Catalyzed Hydrolyses of Acylpyrroles and Acylindoles. Noninvolvement of Protonated Substrates
Cipiciany, Antonio,Linda, Paolo,Savelli, Gianfranco,Bunton, Clifford A.
, p. 4874 - 4879 (1981)
The acid hydrolyses of N-(trifluoroacetyl)pyrrole, -indole, and -tetrahydrocarbazole and of N-acetylindole exhibit rate maxima in H2SO4 (20-40 wt percent, -H0 = 1-2.5) that are not due to exstensive substrate protonation.The reactions have very large ω and φ values, suggesting that there is a large difference in hydration of the initial and transition states.N-(Trifluoroacetyl)pyrrole is hydrated in water, and this evidence and that of hydrogen solvent isotope and salt and acid effects show that acid-catalyzed brekdown of a gem-diol is rate limiting.Rate maxima in acid hydrolyses of other weakly basic substrates can be explained in these terms.
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.
Photoinduced electron transfer in pentacoordinated complex of zinc tetraphenylporphyrin and isoquinoline N-oxide. Crystal structure, spectroscopy and DFT studies
Oberda,Deperasinska,Nizhnik,Jerzykiewicz,Szemik-Hojniak
, p. 2391 - 2399 (2011)
A novel, pentacoordinated complex of (1:1) zinc tetraphenylporphyrin and isoquinoline N-oxide (ZnTPP-IQNO) was synthesized and its crystal structure along with photophysical properties by experimental methods (absorption, steady state and time-resolved emission) in conjunction with DFT and TD DFT calculations were investigated. In ZnTPP-IQNO complex, the isoquinoline N-oxide ligand (IQNO) is directly coordinated to the central zinc atom of the ZnTPP unit through the oxygen atom of the NO group and crystallizes in centrosymmetric triclinic unit, in the space group P1. Particular contacts between the two monomeric units (hydrogen bonds, O...H-C interactions, ...etc.) lead to a supramolecular dimer which forms the layers propagating both along the a and the b-axis. The electronic locally excited and the charge-transfer states of the complex were calculated by TDDFT CAM-B3LYP/6-31G(d,p) method. A surprising presence of the charge transfer states between the Soret and the Q bands leads to excitation energy dissipation processes involving the opening of the radiationless channels of excited ZnTPP-IQNO complex. Emission from the S 1 state (Q band) in ethyl acetate decays accordingly to monoexponential function (1.92 ns) while a bi-exponential decay is found in n-propanol [(2.5 ns (87%); 14.4 ns (13%)] and in the solid state [1.36 ns (67.5%), 7.31 ns (32.5%)].
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
