Synthesis of 1,3,6-Trisubstituted Azulenes Based on the 1-Acyloxyazulene Scaffold

An efficient synthetic route to 1,3,6-trisubstituted azulenes based on the 1-acyloxyazulene scaffold was developed. The 1-position in azulene was substituted in the ring-formation step with a functionalized acyloxy group. Additionally, the 3- and 6-positions of azulene were functionalized with versatile synthetic handles, a halogen atom and a formyl group.