DERIVATIVES OF 14H-NAPHTHO[2,3-A]PHENOTHIAZINE-8,13-DIONE .1. SYNTHESES FROM -(3)SUBSTITUTED-1,4-DIHYDROXY(AMINO)ANTHRAQUINONES

Condensation of 2-substituted-1,4-dihydroxyanthraquinones with 2-amino benzenethiol generally results in the elimination of the 2-substituent and formation of hydroxy-14H-naphtho[2,3-a]phenothiazine-8,13-dione ( I). In addition to the anticipated replacement of labile 2-substituent s such as halogeno, sulphone, carboxamido and t-amino, the elimination of ether, thioether, 1 degrees and 2 degrees-amino and hydroxy groups also occurs. 2-Alkyl substituents are retained, affording the 6-alkyl derivatives (II). 1,4-Dihydroxyanthraquinone undergoes direct thiolat ion and ring closure to I and similar reaction of 1-hydroxy-4-amino- a nd 1-hydroxy-4-arylamino-anthraquinones also gives I, with preferentia l reaction ortho to the amino group. The use of 1-hydroxy(or amino)-2- bromo-4-aminated anthraquinones, however, yields 7-aminated analogues (III). With both the 2-and 3-bromo-derivatives of 1-hydroxy-4-aminoant hraquinone, the reaction proceeds via debromination and subsequent rea ction as with 1-hydroxy-laminoanthraquinone, giving I. The isomeric hy droxy-14H-naphtho[2,3-a]phenothiazine-8,13-dione was obtained via 1,3- dihydroxyanthraquinone.