The first synthesis of monoaza- and diaza-analogues of benzo[a]phenothiazine ring system is achieved under anhydrous conditions by base-catalysed reaction of o-aminoheterocyclic thiones with 2,3-dichloronaphtho-1,4-quinone. If the reactions were carried out in methanol, 2-chloro-3-methoxynaphtho-1,4-quinone was also isolated. The ease of air oxidation of the Na2S2O4 reduced compounds makes them suitable for consideration as vat dyes.
Tetrahedron 12/1986; 42(10):2771-2775. DOI:10.1016/S0040-4020(01)90564-2