175676-54-7Relevant articles and documents
Radical Borylative Cyclization of Isocyanoarenes with N-Heterocyclic Carbene Borane: Synthesis of Borylated Aza-arenes
Liu, Yao,Li, Ji-Lin,Liu, Xu-Ge,Wu, Jia-Qiang,Huang, Zhi-Shu,Li, Qingjiang,Wang, Honggen
supporting information, p. 1891 - 1897 (2021/03/08)
Borylated aza-arenes are of great importance in the area of organic synthesis. A radical borylative cyclization of isocyanoarenes with N-heterocyclic carbene borane (NHC-BH3) under metal-free conditions was developed. The reaction allows the efficient assembly of several types of borylated aza-arenes (phenanthridines, benzothiazoles, etc.), which are difficult to access using alternative methods. Mild reaction conditions, a good functional-group tolerance, and generally good efficiencies were observed. The utility of these products is demonstrated, and the mechanism is discussed.
CF3 oxonium salts, O-(trifluoromethyl)dibenzofuranium salts: In situ synthesis, properties, and application as a real CF3+ species reagent
Umemoto, Teruo,Adachi, Kenji,Ishihara, Sumi
, p. 6905 - 6917 (2008/02/11)
(Chemical Equation Presented) We report in situ synthesis of the first CF3 oxonium salts, thermally unstable O-(trifluoromethyl)- dibenzofuranium salts, which furthermore have different counteranions (BF 4-, PF6-, SbF6 -, and Sb2F11-) and ring substituents (tert-butyl, F, and OCH3), by photochemical decomposition of the corresponding 2-(trifluoromethoxy)biphenylyl-2′- diazonium salts at -90 to -100°C. The yields markedly increased in the order of BF4- 6- 6- 2F11-. The CF3 oxonium salts were fully assigned by means of 1H and 19F NMR spectroscopy at low temperature. The CF3 salts decomposed to form CF4 and dibenzofurans. The half-life times at -60°C of the 2-tert-butyl salts having different counteranions were 29 min for BF4- salt 2d, 36 min for PF6- salt 2c, 270 min for SbF6- salt 2a, and 415 min for Sb2F11- salt 2b. Those at -60°C of the Sb2F11- salts having different 2-substituents were 13 min for F salt 3b, 63 min for H (unsubstituted) salt 1b, and 415 min for tert-butyl salt 2b. Thus, the stability of the CF3 oxonium salts increased in the order of BF4- 6 - 6- 2F 11- and F 3+ species source to the direct O- and N-trifluoromethylations of alcohols, phenols, amines, anilines, and pyridines under very mild conditions. The thermal decomposition method with a mixture of diazonium salt 17a and aryl- or alkylsulfonic acids, pyridine, or pyridines having an electron-withdrawing group also afforded CF3O or CF 3N products. The trifluoromethylation mechanism is discussed and an SN2 mechanism containing the transient formation of free CF 3+ is proposed. Thus, the present study has demonstrated that the exceedingly reactive CF3+ species can be generated much easier than the CH3+ species, contrary to the common sense that CF3+ is extremely difficult to generate in solution.
