Heterocyclization of 2-allylthiobenzimidazoles into derivatives of benzimidazo[2,1-b]-1,3-thiazines

It was found that bromination of 2-allylthiobenzimiduzoles in organic solvents forms products of addition of bromine to the olefin bond-2, 3-dibromopropylthiobenzimidazoles, which spontaneously or on heating cyclize into 3-bromobenzimidazo2,1-b]-1, 3-thiazines or cyclodehydrobromination products — 2H- or 4H-benzimidazo2,1-b]-1, 3-thiazines.Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences of the Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 410–415, March, 1995. Original article submitted December 12, 1994.