The oxidation of benzoylthiourea

Abstract

Oxidation of benzoylthiourea with bromine gives initially N¹,N³-dibenzoyl-α,α-dithiobisformamidine dihydrobromide (5) which, on recrystallization or treatment with polar solvents, rearranges and cyclizes with elimination of ammonium bromide or sulphur to give derivatives of 3H-1,2,4-dithiazole and 1,2,4-thiadiazole respectively. The former reaction is unprecedented in thiourea oxidations and occurs exclusively under suitably chosen conditions.