20830-58-4Relevant articles and documents
Synthesis and reactions of the first cyclopentadienyl isonitriles
Banert, Klaus,K?hler, Frank,Meier, Barbara
, p. 3781 - 3783 (2003)
6-Azidofulvenes without a further substituent in the exocyclic position were transformed into new 1-isocyano- and 2-isocyanocyclopenta-1,3-dienes by photolysis in methanol. These novel functionalized cyclopentadienes are useful building blocks, e.g. as dienes in Diels-Alder reactions.
Contrasting Photolytic and Thermal Decomposition of Phenyl Azidoformate: The Curtius Rearrangement Versus Intramolecular C-H Amination
Wan, Huabin,Xu, Jian,Liu, Qian,Li, Hongmin,Lu, Yan,Abe, Manabu,Zeng, Xiaoqing
, p. 8604 - 8613 (2017/11/24)
The decomposition of phenyl azidoformate, PhOC(O)N3, was studied by combining matrix isolation spectroscopy and quantum chemical calculations. Upon UV laser photolysis (193 and 266 nm), the azide isolated in cryogenic noble gas matrices (Ne and Ar, 2.8 K) decomposes into N2 and a novel oxycarbonylnitrene PhOC(O)N, which was identified by matrix-isolation IR spectroscopy (with 15N labeling) and EPR spectroscopy (|D/hc| = 1.620 cm-1 and |E/hc| = 0.024 cm-1). Subsequent visible-light irradiation (532 nm) causes rearrangement of the nitrene into phenoxy isocyanate PhONCO with complex secondary fragmentation (PhO· + ·NCO) and radical recombination species in matrices. The observation of PhONCO provides solid evidence for the Curtius rearrangement of phenyl azidoformate. In sharp contrast, flash vacuum pyrolysis (FVP) of PhOC(O)N3 at 550 K yields N2 and exclusively the intramolecular C-H amination product 3H-benzooxazol-2-one. FVP at higher temperature (700 K) leads to further dissociation into CO2, HNCO, and ring-contraction products. To account for the very different photolytic and thermal decomposition products, the underlying mechanisms for the Curtius rearrangement (concerted and stepwise) of PhOC(O)N3 and the intramolecular C-H amination of the nitrene in both singlet and triplet states are discussed with the aid of quantum chemical calculations using the B3LYP, CBS-QB3, and CASPT2 methods.
The photochemical transformation and tautomeric composition of matrix isolated benzotriazole
Kiszka, Mariusz,Dunkin, Ian R.,Gebicki, Jerzy,Wang, Hong,Wirz, Jakob
, p. 2420 - 2426 (2007/10/03)
Photolysis of benzotriazole isolated in argon and nitrogen matrices at 12-14 K has been studied by means of UV-visible and IR absorption spectroscopy. Short wavelength irradiation resulted in N-NH bond scission to give diazoimine 3 and minor products: cyanocyclopentadiene 6 and ketenimine 5. The compound 3 was easily bleachable. With 420 nm light, the major pathway was cycloreversion to benzotriazole, but at shorter wavelengths photolysis of 3 led first to the ketenimine product and ultimately to cyanocyclopentadiene. The photoproducts were identified by means of their characteristic IR absorptions. Identification of 3 was additionally supported by comparison of experimental and computed IR transitions, which also indicated that 3 was generated predominantly as its E isomer. Detailed analysis of the benzotriazole IR spectra recorded prior to and after photolysis pointed towards the co-existence of both tautomeric forms, 1H-benzotriazole (1) and 2H-benzotriazole (2), frozen from the gas phase during matrix deposition. An estimate of 1.6:1 was obtained for the gas-phase [1H]:[2H] ratio at ca. 315 K, in fair agreement with another recent estimate. The benzotriazole tautomers exhibited different photoreactivity, but attempts to utilize this in identifying the IR bands of the individual tautomers were hampered by band overlap, and only a few unequivocal assignments could be made.
