Quinoxaline diaryl

The electronic absorption spectra of 2,3-diaryl-3,5,6,7-tetrahydropyrido-[l,2,3-de]quinoxalines have been investigated (65JOC2589). Spectroscopic methods colorimetric (89MI11 92MI12), direct UV and difference UV, and IR [88KFZ(9)1140 89URP1489777] were developed for the quantita-... 

Both the C and N chemical shifts of a number of quinoxalines substituted at position 2 with the n-electron excess 2 -benzo[ ]furanyl substituent, which has at position 3 a hydroxy or amino group, could be satisfactorily calculated by the GIAO method on the basis of HF and DFT ab initio structures. Quantum mechanical calculations using the 3-21 G(d) basis-set were performed on some p-substituted diaryl tellurides and aryl Me tellurides, and the corresponding cationic radicals of these compounds. Calculated relative radical stabilization energies were shown to correlate with experimental data, and the peak oxidation potentials and Te chemical shifts were... 

Dipyrrolylquinoxalines with extended ehromophores are efficient fluorimetric sensors for pyrophosphate. The Stille coupling of 5,8-dibromo-2,3-di(pyrrol-2-yl) quinoxaline with aryItributylstannane produced 5,8-diaryl substituted quinoxalines 205 as possible sensors [100]. 

Table 1. 2-Aryl(heteroaryl)- and 2,3-Diaryl(diheteroaryl)quinoxalines. . . 237...

Chung et al. devised a facile one-pot synthesis of quinoxalines, treating 1,2-diaminobenzenes and internal alkynes with (diacetoxyiodo)benzene as a source of hypervalent iodine and pivalic acid in DMSO at 140 °C (Scheme 51) (13T9735). The resulting diaryl quinoxalines 124 were obtained in good-to-high yields. 

Unsymmetrical benzils, Ar -COCO-Ar, have been prepared via NHC-catalysed nucleophilic aroylation of A-phenylimidoyl chlorides, Ar -C(C1)=N-Ph, by aromatic aldehydes (Ar -CHO), to give the imine, Ari-C(=NPh)-CO-Ar, followed by hydrolysis. Conveniently done in one pot with sodium hydride in refluxing THF, the further in situ conversion of the benzils into 2,3-diaryl-quinoxalines and -pyrazines has been achieved by double-condensation with 1,2-diamines. 

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