Benzo- and naphthoimidazoxadiazolediene, naphthobisthiazole as well as naphthothiazine derivatives from 1-acylthiosemicarbazides

Abstract

1-Acylthiosemicarbazides 1a-d reacted with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (2a), 2,3,5,6-tetrachloro-1,4-benzoquinone (2b), 2,3-dichloro-1,4-naphthoquinone (3a) and 2,3-dicyano-1,4-naphthoquinone (3b) in ethyl acetate with admission of air to form benzo-and naphtho-imidazoxadiazoles (5, 6, 11), naphthobisthiazoles (12a-d), naphthothiadiazines (13a-d) as well as 2,3,7,8-tetrachlorothianthrene-1,4,6,9-tetraone (7). Rationales for the observed conversions are presented.