Short Syntheses of 1-Substituted Dibenzothiophenes and 3-Substituted Naphthothiophenes

The 1-substituted dibenzothiophene motif is an unusual substitution pattern. We demonstrate a simple one-pot preparation of 1-lithiodibenzothiophene via a cascade of two benzyne additions and conversion to the aldehyde, boronic ester, and iodide. This work avoids the use of precious metals or tert-butyllithium and is shorter than existing routes to these compounds. We also report an improved route to the isomeric 3-substituted naphthothiophene scaffold. These protocols will allow rapid access to families of these two related heteroacenes.