Construction of Structurally Rigid Azulen-6-ones via Migratory Rearrangement of Spirocycles and Their Photophysical Studies

We report the synthesis of polysubstituted 1 ,1,2,3tetraarylazulen-6-ones through the ring opening and scaffold rearrangement of spirocycles in the presence of ferric chloride under ambient conditions. Control experiments shown that this reaction may proceeded through a radical cation mechanism and futher theoretical calculation revealed that the electronic distribution of the radical cation intermediate dominated this oxidative rearrangement instead of dehydrogenation. It is noteworthy that some interesting photophysical properties, including aggregation-induced emission, halochromism, and two-photon fluorescence, were discovered for the azulen-6-one 2a, making them to work as promising functional materials in optical-related fields.

Automated summary

This study reports the synthesis of polysubstituted azulen-6-ones through ring opening and scaffold rearrangement of spirocycles under the catalysis of ferric chloride at ambient conditions. Control experiments suggest a radical cation mechanism for the reaction, with theoretical calculations indicating the crucial role of electronic distribution in the oxidative rearrangement. Azulen-6-one 2a exhibits interesting photophysical properties, such as aggregation-induced emission, halochromism, and two-photon fluorescence, making them promising functional materials in optical-related fields.