1-Phenylselanylazulenes: synthesis and selenium atom oxidation

The phenylselanylation of azulene with PhSeCl or PhSeBr was reported. Clean electrophilic substitution of azulene in positions 1 and/or 3 occurred with the first reagent whereas with PhSeBr a complex mixture of products was generated suggesting a radicalic mechanism. The influence on the reaction route of the substituent attached at position 1 of azulene, or of the alkyl positions in alkylated azulenes was investigated. 1-Phenylselanylazulene and 1,3-bis(phenylselanyl)azulene were oxidized using sodium metaperiodate. The oxidation took place at selenium atom and afforded azulenes substituted with PhSe(O) and/or PhSe(O-2) groups in positions 1 and/or 3. The magnetic and electronic spectra as well as the electrochemical oxidation and reduction potentials of the obtained products were recorded and the results were briefly discussed. .