29005-25-2Relevant academic research and scientific papers
Rearrangements of 4-Quinolylcarbene, 3-Quinolylcarbene, and 2-Quinolylcarbene to 1-Naphthylnitrene and Cyanoindenes by Falling Solid Flash Vacuum Pyrolysis
Aylward, Nigel,Kvaskoff, David,Becker, Jürgen,Wentrup, Curt
, p. 4609 - 4615 (2016/07/06)
The relationship between 4-quinolylcarbene 17, 3-quinolylcarbene 21, 2-quinolylcarbene 25, and 1-naphthylnitrene 35 has been explored experimentally and computationally. The diazomethylquinolines generated from (5-tetrazolyl)quinolines or 1,2,3-triazolo[1,5-a]quinoline by conventional flash vacuum pyrolysis (FVP) were observed by IR spectroscopy. The carbenes were generated by falling solid flash vacuum pyrolysis (FS-FVP). 4-Quinolylcarbene 17 was found to rearrange to 3-quinolylcarbene 21 and then to 2-quinolylcarbene 25, and finally via 1-naphthylnitrene 35 to 1-cyanoindene 36, which then isomerizes to 3- and 2-cyanoindenes 12 and 13. The thermal rearrangement of 2-quinolylcarbene to 1-naphthylnitrene was verified by ESR spectroscopy. The reaction mechanism has been elucidated with the help of calculations of the structures and energies of the quinolylcarbenes and 1-naphthylnitrene and the intervening aza-benzobicyclo[4.1.0]heptatrienes, aza-benzocycloheptatetraenes, and aza-benzocycloheptatrienylidenes and the transition states connecting them at the B3LYP/6-31G? level. The nonobserved 1,2-hydrogen shifts in aza-benzocycloheptatetraenes/aza-benzocycloheptatrienylidenes are found to have very high activation barriers.
Rearrangement of 2-Quinolyl- and 1-Isoquinolylcarbenes to Naphthylnitrenes
Lan, Nguyen Mong,Burgard, Riko,Wentrup, Curt
, p. 2033 - 2036 (2007/10/03)
2-Quinolylcarbene 23 and 1-isoquinolylcarbene 33 are generated by flash vacuum thermolysis (FVT) of the corresponding triazolo[1,5-a]quinoline and triazolo[5,1-a]isoquinoline 19 and 29, as well as 2-(5-tetrazolyl)quinoline and 1-(5-tetrazolyl)isoquinoline 20 and 30, respectively. These carbenes rearrange to 1- and 2-naphthylnitrene 21 and 31, respectively, and the nitrenes are also generated by FVT of 1- and 2-naphthyl azides 18 and 28. The products of FVT of both the nitrene and carbene precursors are the 2- and 3-cyanoindenes 26 and 27 together with the nitrene dimers, viz. azonaphthalenes 25 and 35, and the H-abstraction products, aminonaphthalenes 24 and 34. All the azide, triazole, and tetrazole precursors yield 3-cyanoindene 26 as the principal ring contraction product under conditions of low FVT temperature (340-400 °C) and high pressure (1 Torr N2 as carrier gas for the purpose of collisional deactivation). This ring contraction reaction is strongly subject to chemical activation, which caused extensive isomerization of 3-cyanoindene to 2-cyanoindene under conditions of low pressure (10-3 Torr). 2-Cyanoindene is calculated to be ca. 1.7 kcal/mol below 3-cyanoindene in energy; accordingly, high-temperature FVT of these cyanoindenes always gives mixtures of the two compounds with the 2-cyano isomer dominating. Photolysis of trizolo[1,5-a]quinoline 19 and triazolo[5,1-a]isoquinoline 29 in Ar matrixes causes partial ring opening to the corresponding 2-diazomethylquinoline 19′ and 1-diazomethylisoquinoline 29′. The photolysis of the former gives rise to a small amount of the cyclic ketenimine 22, the intermediate connecting 2-quinolylcarbene and 1-naphthylnitrene.
Benzothiet-2-ones: Synthesis, Reactions, and Comparison with Benzoxet-2-ones and Benzazetin-2-ones
Wentrup, Curt,Bender, Harald,Gross, Gerhard
, p. 3838 - 3847 (2007/10/02)
Benzothiet-2-one (5) is obtained as a neat solid, stable below -20 deg C(-45 deg C in solution), by flash vacuum pyrolysis of benzothiophene-2,3-dione (9).Naphthothiet-2-one (21) and naphthothiet-1-one (42) are obtained as stable crystalline solids in near-quantitative yields from the corresponding naphthothiophenediones 20 and 41.Naphthooxet-2-one (31) and naphthoazetin-2-one (36) were generated and observed by IR spectroscopy to be stable below -40 deg C and 0 deg C, respectively.The thietones, oxetones, and azetinones undergo rapid ring-opening reactions with methanol to give the corresponding carboxylic acid esters.They undergo thermal CO elimination with concomitant Wolff-type ring contraction to thioketenes (17, 25, 45), ketenes (30), and nitriles (37), respectively.The di-, oligo-, and polymerization of the thietones has been elucidated.Naphthothiet-1-one (42) reacts with 1-thiocarbonyl-1H-indene (45) to give cycloaddition product 46.Naphthothietones 21 and 42 react with dicyclohexylcarbodiimide to furnish 2-imino-1,3-thiazin-4-one derivatives 47 and 49.
