347-92-2Relevant academic research and scientific papers
Synthesis of Nitrogen-Containing Polyaromatics by Aza-Annulative π-Extension of Unfunctionalized Aromatics
Itami, Kenichiro,Ito, Hideto,Kawahara, Kou P.,Matsuoka, Wataru
supporting information, p. 6383 - 6388 (2020/03/13)
Nitrogen-containing polycyclic aromatic compounds (N-PACs) are an important class of compounds in materials science. Reported here is a new aza-annulative π-extension (aza-APEX) reaction that allows rapid access to a range of N-PACs in 11–84 % yields from readily available unfunctionalized aromatics and imidoyl chlorides. In the presence of silver hexafluorophosphate, arenes and imidoyl chlorides couple in a regioselective fashion. The follow-up oxidative treatment with p-chloranil affords structurally diverse N-PACs, which are very difficult to synthesize. DFT calculations reveal that the aza-APEX reaction proceeds through the formal [4+2] cycloaddition of an arene and an in situ generated diarylnitrilium salt, with sequential aromatizations having relatively low activation energies. Transformation of N-PACs into nitrogen-doped nanographenes and their photophysical properties are also described.
The impact of cation structure upon the acidity of triazolium salts in dimethyl sulfoxide
Konstandaras, Nicholas,Dunn, Michelle H.,Guerry, Max S.,Barnett, Christopher D.,Cole, Marcus L.,Harper, Jason B.
, p. 66 - 75 (2019/12/26)
A series of triazolium salts, selected for their varying electronic and steric properties, were prepared and their pKa values were determined in DMSO at 25 °C using the bracketing indicator method. The effect of each systematic structural variation upon the acidity of the triazolium cation has been considered, in particular examining the effects of systematically altering electronic properties, quantified through the use of Hammett σ parameters. The first pKa value for an azolium salt that generates a mesionic carbene is also reported. These new data allow for the selection of appropriate bases for the deprotonation of such triazolium salts and the potential to correlate the pKa values determined herein with the nucleophilicity of the corresponding carbenes.
Silver(II) oxide-mediated synthesis of 2,4-diarylquinazolines
Cheung, Wing,Patch, Raymond J.,Player, Mark R.
supporting information, p. 2368 - 2371 (2018/05/25)
A single-pot procedure for the synthesis of 2,4-diarylquinazolines is described which involves a silver oxide-mediated C–H activation/C–N bond formation process. The generality of this method with respect to substituent effects is presented along with studies leading to process optimization. Mechanistic investigations provide support for the involvement of radical intermediates in the reaction process.
Solvent/oxidant-switchable synthesis of multisubstituted quinazolines and benzimidazoles via metal-free selective oxidative annulation of arylamidines
Lin, Jian-Ping,Zhang, Feng-Hua,Long, Ya-Qiu
supporting information, p. 2822 - 2825 (2014/06/23)
A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp3)-C(sp2) and C(sp 2)-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp3C-H/sp2C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.
Cyclizations. Part 1. Electrochemical and Photochemical Reactions of 1-(4-Fluorophenyl)-5-(2-halogenophenyl)tetrazoles
Donnelly, Shileen,Grimshaw, James,Trocha-Grimshaw, Jadwiga
, p. 1557 - 1562 (2007/10/02)
Electrochemical reduction of the title compounds, where the halogen substituent is Cl, Br or I, leads to cleavage of the carbon-halogen bond to leave a phenyl radical.Competition then follows between intramolecular radical substitution giving 7-fluorotetrazolophenanthridine and further reduction of the radical, then protonation, giving 1-(4-fluorophenyl)-5-phenyltetrazole.Substitution predominates but reduction and protonation becomes a more competing reaction when the halogen is Br or I.Photochemical reaction of the title compounds shows competition between carbon-halogen bond cleavage to give 7-fluorotetrazolophenanthridine and loss of nitrogen followed by cyclization to give 2-halogenophenyl-5-fluorobenzimidazole.Carbon-halogen bond cleavage predominates and becomes the only reaction when the halogen is I.The fluorine substituent allows the determination of product yields by 19F NMR spectroscopy.
