Azulene‐Substituted Pyranylium Salts. Syntheses and Products Characterization.

Abstract

The synthesis of 4-azulene-substituted 2,6-diphenyl-and 2,6-dimethyl-pyranylium salts and 2-azulenesubstituted 4,6-dimethyl-pyranylium salts by nucleophilic substitution at pyranylium moiety with various azulenes was studied. The starting materials for 2,6-diphenyl derivatives were 4 chlorinated pyranylium salts. They were obtained by the halogenation with PCl 5 of corresponding pyranones and were used either in situ or after separation. For the synthesis of dimethyl derivatives the corresponding pyranones were treated with POCl 3 and the resulted intermediate was reacted in situ with azulene. In the aim to study the influence of dihedral angle between azulene and pyranylium planes on the recorded spectra, both moieties were adequately substituted. The obtained results were in accord with the calculated values.