Selenabenzenes 12a–c with two electron-withdrawing groups (EWGs) at the 2- and 6-positions were synthesized from dihalides 1a, 1b and 1c′via seven steps and isolated as stable compounds at room temperature. According to X-ray structural analysis of the dibenzoyl derivative 12c, the six-membered ring containing a selenium atom is almost planar and the structure of the selenium atom is tetrahedral with
Selenabenzenes with two electron-withdrawing groups at 2,6-positions 9a–c were isolated and stable at room temperature and underwent the thermal rearrangement giving 2- and 4-methylselenines 13 and 14 and the oxygenation reaction giving dienone 15 and selenin-4-one 16.