A New Method for the Synthesis of Nonsymmetrically Substituted Bis(azulen‐1‐yl) Ketones

The 1‐(3‐methylazulen‐1‐yl)alkan‐1‐ones, when oxidized with excess 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (=4,5‐dichloro‐3,6‐dioxocyclohexa‐1,4‐diene‐1,2‐dicarbonitrile; DDQ) in aqueous acetone in the presence of 1‐(3‐demethylazulen‐1‐yl)alkan‐1‐ones, form the corresponding unsymmetrically substituted bis(3‐acylazulen‐1‐yl)methanones in good to excellent yields ( Schemes 4, 5, 7 , and 10 ). Intermediates are the corresponding disubstituted methane derivatives, which are formed by radical and radical‐cation recombination ( Scheme 6 ). The 1‐(3‐methylazulen‐1‐yl)alkan‐1‐ones can as well be coupled oxidatively with azulene itself, benz[ a ]azulene, or 1,3‐dimethoxybenzene ( Schemes 9–11 ).