Synthesis of Boronate-Based Benzo[fg] tetracene and Benzo[hi]hexacene via Demethylative Direct Borylation

A demethylative direct borylation is reported, which was applied to the synthesis of benzo[fg] tetracenes containing boronate ester, amide, and thioester substructures. Depending on the heteroatom adjacent to boron, the molecules showed characteristic photophysical properties, molecular arrangements, and chemical stabilities. The key to the successful synthesis is the appropriate choice of the boron source and Bronsted base. The versatility of the direct borylation was demonstrated by the synthesis of a boronate-based benzo[hi] hexacene.