7126-38-7Relevant academic research and scientific papers
4-Pyridylnitrene and 2-pyrazinylcarbene
Wentrup, Curt,Reisinger, Ales,Kvaskoff, David
, p. 754 - 760 (2013/06/27)
Both flash vacuum thermolysis (FVT) and matrix photolysis generate 2-diazomethylpyrazine (22) from 1,2,3-triazolo[1,5- a]pyrazine (24). FVT of 4-azidopyridine (18) as well as of 24 or 2-(5-tetrazolyl)pyrazine (23) affords the products expected from the nitrene, i.e., 4,4'-azopyridine and 2- and 3-cyanopyrroles. Matrix photolyses of both 18 and 24 result in ring expansion of 4-pyridylnitrene/2-pyrazinylcarbene to 1,5-diazacyclohepta-1,2,4,6-tetraene (20). Further photolysis causes ring opening to the ketenimine 27.
2-pyridylnitrene and 3-pyridazylcarbene and their relationship via ring-expansion, ring-opening, ring-contraction, and fragmentation
Kvaskoff, David,Bednarek, Pawel,Wentrup, Curt
scheme or table, p. 1600 - 1611 (2010/05/01)
(Figure Presented) Photolysis of triazolo[1,5-b]pyridazine 8 isolated in Ar matrix generates diazomethylpyridazines 9Z and 9E and diazopentenynes 11Z and 11E as detected by IR spectroscopy. ESR spectroscopy detected the 3-pydidazylcarbene 10 as well as pent-2-en-3-yn-l-ylidene 12 formed by loss of one and two molecules of N2, respectively. Further photolysis caused rearrangement of the carbenes to 1,2-pentadien-4-yne 13 and 3- ethynylcyclopropene 14. Flash vacuum thermolysis (FVT) of 8 at 400-500 °C with Ar matrix isolation of the products yielded 13, 14, and 1,4-pentadiyne 15. At higher temperatures, glutacononitriles 27Z and 27E were formed as well together with minor amounts of 2- and 3-cyanopyrroles 28 and 29. Tetrazolo[1,5-a]pyridine/2-azidopyridine 22T/22A yields 2-pyridylnitrene 19 as well as the novel open-chain cyanodienylnitrene 23 and the ring-expanded 1,3-diazacyclohepta-l,2,4,6-tetraene 21 on short wavelength photolysis. Nitrenes 19 and 23 were detected by ESR spectroscopy, and cumulene 21 by IR and UV spectroscopy. FVT of 22T/22A also affords 2-pyridylnitrene 19 and diazacycloheptatetraene 21, as well as glutacononitriles 27Z,E and 2- and 3-cyanopyrroles 28 and 29. Photolysis of 21 above 300 nm yields the novel spiroazirene 25, identified by its matrix 1R spectrum. The reaction pathways connecting the four carbenes (10Z,E and 12Z,E) and three nitrenes (19, 23EZ, and 23ZZ) in their open-shell singlet and triplet states are elucidated with the aid of theoretical calculations at DFT, CASSCF, and CASPT2 levels. Three possible mechanisms of ring-contraction in arylnitrenes are identified: (i) via ring-opening to dienylnitrenes, (ii) concerted ring-contraction, and (iii) via spiroazirenes 25, whereby (i) is the energetically most favorable.
Chemistry of α-Amino Nitriles. Exploratory Experiments on Thermal Reactions of α-Amino Nitriles
Xiang, Yi-Bin,Drenkard, Susanne,Baumann, Karl,Hickey, Deirdre,Eschenmoser, Albert
, p. 2209 - 2250 (2007/10/02)
The paper extends a previously published report on chemical properties of α-amino nitriles and of members of the C3H4N2 ensemble (Scheme 1) as observed in experiments carried out under non-aqueous conditions.The reactions investigated and the observations made are summarized in some detail in the English footnotes (*) referring to Schemes 1-17 and Fig. 1.
PYRROLE CHEMISTRY. PART XXIX. A RE-EXAMINATION OF THE DECARBOXYLATION OF 4-ACETYL-, 4-FORMYL- AND 4-CYANO-PYRROLE-2-CARBOXYLIC ACIDS
Anderson, Hugh J.,Clase, J. Andrew,Loader, Charles E.
, p. 401 - 408 (2007/10/02)
Decarboxylation of the readily available 4-acyl-2-pyrrolecarboxylic acids has been neglected owing to the poor yields reported in the literature.This study shows that high yields are possible under the correct reaction conditions.
