Synthesis of 2,3,7,8-tetramethyldibenzofuran

3,4,3′,4′-Tetramethyldiphenyl ether readily forms 2,2′-dihalo derivatives on bromination and iodination. Heating 2,2′-diiodo-4,5,4′,5′-tetramethyldiphenyl ether with copper powder or oxidation, of 2,2′-dilithio-4,5,4′,5′-tetramethyldiphenyl ether gives 2,3,7,8-tetramethyldibenzofuran, the structure of which was proved by alternative synthesis from 2,2′-dinitroand 2,2′-diamino-4,5,4′,5′-tetramethyldiphenyls.