A Convenient and Single‐Step Synthesis of Substituted 12H‐Quinoxalino‐[2,3‐b][1,4]benzothiazines and ‐benzoxazines

Angular heterocycles: a convenient synthesis of 6-N-(acetylanilino)-5H-benzo[a]phenothiazin-5-one, 6-N-(acetylanilino)-5H-benzo[a]phenoxazin-5-ones and their derivatives

Angular heterocycles. Utilization of arylaminonaphthoquinones in the synthesis of benzophenothiazines

Cycloaddition reaction of 2-aryl-1,4-benzoquinones 1a-d with a number of different dienes, namely 2,3-dimethylbutadiene; 1,4-diphenylbutadiene and anthracene yield 2-aryl-6,7-dimethyl-1,4- naphthoquinones 3a,b; 2,5,8-triphenyl-1,4-naphthoquinone 4 and 2-aryl-1,4,9,10-tetrahydro-9,10-o-benzoanthracene-1,4-dione 5, respectively were investigated. In addition, the cycloaddition reaction of 2-aryl-1,4-benzoquinones 1d,e with 2,3-dimethylbutadiene was also investigated to yield 2-aryl-5,8-dihydro-6,7-dimethyl-1,4-naphthohydroquinones 2a,b. Cyclocondensation reactions of Diels-Alder adducts 2b, 3b, 5a with ethylenediamine, o-substituted primary aromatic amines gave quinoxaline, phenazine, phenoxazine and phenothiazine ocyclic derivatives 6–14.

Synthesis of Arylnaphthoquinones and Their Reactions with o‐Substituted Primary Aromatic Amines

A number of substituted endo-12,17-O-phenylene-12,17-dihydronaphtho[2,3-a][1,4]benzothiazino[3,2′-c]phenothiazines (4) and substituted endo-8,13-O-phenylene-8,13-dihydro-6-chloro-7H-naphtho[2,3-a]phenothiazin-7-ones (5) were synthesised by the condensation reaction of endo-9,10-O-phenylene-2,3-dichloro-9,10-dihydro-1,4-anthraquinone (1) with substituted 2-aminothiophenol (2) and their zinc mercaptides (3), respectively. These reactions are rationalized and pertinent IR and UV data are also given.

Nandlal Agarwal

Papers

Thin-layer chromatography of some new angular heterocyclics