Synthesis and Reactions of Some New Benzo[ a ]phenothiazine‐3,4‐dione Derivatives

The reaction of 2,3‐dihydro‐2,3‐epoxy‐1,4‐naphthoquinone ( 4 ) with substituted anilines furnished the corresponding benzo[fused]heterocyclic derivatives 5 , 6 , 6a , 6b , 7 , 8 . Furthermore, treatment of benzo[ a ]phenothiazine derivative 7 with halo compounds, namely, ethyl bromoacetate, phenacyl bromide, dibromoethane, or chloroacetone afforded ether derivatives 11 , 12 , 13 , 14 , respectively. Moreover, the reaction of 11 with o ‐substituted aniline gave the corresponding benzo[ a ]phenothiazin‐5‐one derivatives 15 , 16 , 17 and benzo[ d ][1,3]oxazin‐4‐one 18 , respectively. Finally, the chromenone derivative 19 was synthesized via the reaction of ester derivative 11 with salicyaldhyde in refluxing pyridine. The newly synthesized compounds were characterized by spectroscopic measurements (IR, 1 H NMR, 13 C NMR, and mass spectra).