OXIDATION OF SELENOPHENES

Abstract

Abstract Oxidation of a series of selenophenes (1) with a variety of oxidizing agents was investigated. Oxidation of 1 with 2 molar amounts of dimethyldioxirane (DMD) generally gave the corresponding selenophene 1,1-dioxides (2) in good yields except for a few cases where 1 carry electron-withdrawing substituents. Isolation of selenophene 1-oxide intermediates on oxidation with an equimolar amount of DMD was difficult because of their thermally labile nature, only oxidation of benzo[b)selenophene gave the isolable 1-oxide in a good yield. Meanwhile, oxidation of 1 with in-chloroperbenzoic acid did not give the selenophene 1,1-dioxides 2, but led instead to oxidation products containing no selenium atoms, resulting from ring opening of the selenophene. Thus, for example, oxidation of tetraarylselenophenes gave (Z)-1,2,3,4-tetraaryl-2-butene-1,4-diones as the principal product. Also in this oxidation, the only exception was the oxidation of benzo[bJselenophene which afforded the corresponding 1-oxide.