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The dehydrogenation of some diazoamino-compounds with lead tetra-acetate in aromatic solvents has been shown to give rise to mixtures of biaryls and azo-compounds. The reaction of diazoaminobenzene, in monosubstituted benzene derivatives as solvents, gives azobenzene and mixtures of isomeric biphenyls as products. The isomer ratio for the biphenyls suggests that they are formed by substitution of intermediate phenyl radicals in the aromatic solvent. The dehydrogenation of 1,1-di-2-naphthyltriazen in benzene led to 2-phenylnaphthalene and dibenzo[a,h]phenazine as products. The latter product is also obtained from the thermal decomposition of 2-naphthyl azide. These latter results indicate the intervention of nitrenes as intermediates. The electron paramagnetic resonance spectrum of the reaction mixture of 1,3-diphenyltriazen with lead tetra-acetate exhibited a triplet with a coupling constant of about 10 gauss, which may be indicative of an intermediate triazenyl radical, which would break down to afford a phenyl radical, phenylnitrene, and nitrogen.

The phenylation of thiophen, carried out with several phenylating agents, afforded in each case a mixture of 2- and 3-phenylthiophens the proportions of which were in the range 90—95 : 10—5. The rates of substitution of thiophen relative to benzene by substituted phenyl radicals, generated by the aprotic diazotization of the anilines with pentyl nitrite have been found to follow, qualitatively, the order expected on the basis of the theory of polarized aryl radicals. A linear correlation has been found to hold between the partial rate factors for the 2-position of thiophen, and the substituent σ° parameters.

The reaction of thiophen with phenylazotriphenylmethane has been investigated. The percentage of the 2-phenyl-thiophen relative to that of the 3-isomer is considerably lower than those obtained with other phenylating agents and is highly dependent on the experimental conditions as well as on the working-up of the reaction mixtures. This is attributed to the trapping of the σ-complex leading to the 2-phenylthiophen by the triphenylmethyl radical to give two isomeric 2,5-dihydro-2-phenyl-5-triphenylmethylthiophens.

The spectrum of the title compound is reported. This radical can be viewed as a triarylmethyl radical in which one of the aryl groups is electrically charged.

We described the optimization, by molecular modelling, of small pyrazole derivatives, as kinase inhibitors, obtained through a 1,3-dipolar cycloaddition between nitrile imines and functionalized acetylenes. The two compounds, selected as potential agents active against hepatocellular carcinoma (HCC) were then evaluated in vitro for their biological activity on HCC-derived cell lines. The compounds show a promising inhibitory growth efficacy (IC 50 50–100 μM) in SNU449 cell line, as well as block of cell cycle progression and induction of apoptosis, and can be considered as lead compounds for further SAR developments.