How is Benzothieno[3,2-b][1]benzothiophene (CAS: 248-70-4) typically synthesized?

Benzothieno[3,2-b][1]benzothiophene (CAS: 248-70-4) is typically synthesized via a two-step process involving the reaction of benzothiophene with a brominating agent followed by a nucleophilic substitution reaction. The key steps involve the formation of a brominated intermediate and subsequent reaction with a butadienyl derivative or similar nucleophile. The yield and selectivity of the reaction can be enhanced through the use of appropriate catalysts and solvents.