4175-70-6Relevant articles and documents
Intriguing enigma of nitrobenzofuroxan's ‘Sphinx’: Boulton-Katritzky rearrangement or unusual evidence of theN-1/N-3-oxide rearrangement?
Boga, Carla,Bordoni, Silvia,Calvaresi, Matteo,Chugunova, Elena,Iannuzzo, Leonardo,Micheletti, Gabriele,Telese, Dario
, p. 34670 - 34680 (2020/10/08)
The SEAr/SNAr reaction between 7-chloro-4,6-dinitrobenzofuroxan (ClDNBF) and 2-morpholinyl-, 2-piperidinyl-, or 2-pyrrolidinylthiazole afforded unexpectedly two isomeric products, bearing the benzofuroxanyl moiety bound to the C-5 carbon atom of the thiazole ring. The relative ratio for the two isomers was dependent on temperature and solvent, suggesting the occurrence of an equilibrium between the two novel species. In order to investigate their structure and to design a plausible mechanistic pathway, a series of synthetic and spectroscopic experiments was planned. The isomer's structure was unambigously assigned when the reduction of furoxanyl to the furazanyl ring of the products gave exclusively a single species whose NMR data were coincident with those obtained by reacting the starting 2-aminothiazole derivatives with the 7-chloro-4,6-dinitrobenzofurazan (ClDNBZ). Possible mechanistic pathways might involveN-1-/N-3 oxide tautomerism or Boulton-Katritzky rearrangement and the current study is the first attempt to compare these two reactions. The data collected agree with the first one and DFT calculations permitted also a significant correlation with13C NMR experimental data and the assignment of the structure of each isomer. Finally, only one Meisenheimer intermediate for each electrophile/nucleophile combination was isolated by coupling the 2-aminothiazole derivatives with 4,6-dinitrobenzofuroxan (DNBF).
Pd-PEPPSI-IPentAn Promoted Deactivated Amination of Aryl Chlorides with Amines under Aerobic Conditions
Huang, Fei-Dong,Xu, Chang,Lu, Dong-Dong,Shen, Dong-Sheng,Li, Tian,Liu, Feng-Shou
, p. 9144 - 9155 (2018/07/21)
We report herein a highly efficient Pd-catalyzed amination by "bulky-yet-flexible" Pd-PEPPSI-IPentAn complexes. The relationship between the N-heterocyclic carbenes (NHCs) structure and catalytic properties was discussed. Sterically hindered (hetero)aryl chlorides and a variety of aliphatic and aromatic amines can be applied in this cross-coupling, which smoothly proceeded to provide desired products. The operationally simple protocol highlights the rapid access to CAr-N bond formation under mild conditions without the exclusion of air and moisture.
BENZOXAZOLE DERIVATIVES
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Page/Page column 63-64, (2009/10/01)
It is intended to provide a benzoxazole derivative or a pharmaceutically acceptable salt or solvate thereof which is useful in the early diagnosis of a conformation disease; a composition or a kit containing the same for diagnosing a conformation disease; a medical composition for ttreating and/or preventing a conformation disease; and so on.
Synthesis and Characterization of 1,3-Bis-(2-dialkylamino-5-thiazolyl)-Substituted Squaraines and Their 2-(Dialkylamino)thiazole Precursors
Keil, D.,Hartmann, H.
, p. 979 - 984 (2007/10/02)
By condensation of squaric acid (1) with 2-(dialkylamino)-substituted thiazoles 8 a novel type of heterocyclic-substituted squaraines of the general structure 9 was prepared in moderate yield mostly.The squaraines 9 obtained are sparingly soluble in the most organic solvents and exhibit, in these solvents, narrow absorption bands in the visible range at about 620-700 nm.In dispersed form, the absorption bands of the squaraines 9 are, however, broadened and shifted into the NIR region at about 900 nm.These unique properties of the new squaraines 9 suggest the use of these dyes as spectral sensitizers for laser-driven data recording or data storage media. - Key Words: Squaraines/ Squaric acid/ Thiazoles/ Sensitizers
Kinetic and Mechanistic Studies of the Reactions between 2-Nitrothiazole, 2-Nitrobenzothiazole and some Nucleophiles
Forlani, Luciano
, p. 1699 - 1702 (2007/10/02)
Kinetic data for the reactions between some 2-nitrothiazoles and nucleophiles (alkoxide and piperidine) are reported.The kinetic behaviour of the nitro group parallels that of the more usual leaving groups and a two-step mechanism involving nucleophilic aromatic substitution may be suggested to be in operation.A change of counter ion (Li(1+), Na(1+), K(1+) of the anionic nucleophile indicates that the presence of the ion pairs partially favours reactivity, probably by interaction with the nitro group.The autocatalytic behaviour of the reactions between 2-nitrothiazole and piperidine is explained by the presence of an interaction between the substrate and the nucleophile in an equilibrium preceding the substitution process.Comparison of the nucleofugicity of nitro and chloro groups (as leaving groups) indicates that the presence of hydrogen bonds between the leaving group and the solvent (or the nucleophile) produces considerable variations in the observed reactivities.
