Filip Chiraleu

Azulene-1-azopyridine 1′-oxides

The coupling between diazonium salts obtained from the three aminopyridine 1-oxides and azulene allowed the synthesis in good yield of the corresponding azulene-1-azopyridine 1 0 -oxides, which were characterised. The reduction and the methylation of the products were studied. The last two reactions allowed to synthesize azulene-1-azo-2 0 -pyridine and its alkylpyridinium salts, unavailable on other way. The UV–vis spectra of azulene-1-azopyridines were compared with those of the corresponding N-oxides and pyridinium salts. For the N-oxides the solvatochromic effect was evidenced. # 2003 Elsevier Science Ltd. All rights reserved.

New amino-nitroxide spin labels.

Stable free mono- and diradicals containing reactive primary or secondary amino groups in the side-chain have been synthesized by transesterification of amino-substituted esters with paramagnetic alcohols or from spin-labeled acid derivatives and amines. In the second approach the new radical 18 (1-oxyl-3-(2-bromoethoxycarbonyl)-2,2,5,5-tetramethylpyrroline) is proposed as an efficient alkylating species. The nitroxides described are pH-sensitive spin probes and spin labels potentially useful for a diversity of ESR applications in chemistry and biology. New spin-labeled tyramine 16 (N-(1-oxyl-3-carbonyl-2,2,5,5-tetramethyl-pyrroline)tyramine) was successfully employed in a novel assay of protein oxidative damage.