Synthesis and Optical Properties of Azuleno[1,2-b]benzothiophene and Selenophene

Abstract

Benzothiophene-and benzoselenophene-fused azulene derivatives were synthesized by Cu-catalyzed tandem cyclization via the Ullmann-type S/Searylation and Csp 2 -H chalcogenation of 2-(2′-bromophenyl)azulene. The maximum absorption of tetracyclic products was red-shifted from that of 2-phenylazulene, which does not contain a bridged chalcogen atom. Single-crystal X-ray analysis of azuleno[1,2-b]benzoselenophene revealed that the benzo[b]selenophene and azulene rings are almost coplanar.Azulene-fused heterocycles are building blocks for natural products and organic materials; hence, their