The Synthesis of the Benzofuro[2,3-b]benzofuran Derivative

The synthesis of 2,9-dimethoxybenzofuro-[2,3-b]benzofuran from its 5a,10b-dihydro-compound was carried out by bromination with N-bromosuccinimide, followed by dehydrobromination. The attempted preparation of 2,9-dimethyl-, 2,9-dichloro-, and 2,4,7,9-tetrachloro-derivatives was unsuccessful.