Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 6. Mitteilung . Über die Reaktivität des Cyclohexylrestes in 2‐Chlor‐3‐[(1‐cyclohexyl‐6‐fluor‐3‐methyl‐1 H ‐chinoxalin‐2‐yliden)methyl]‐1,4‐naphthochinon

Ring Closure in Quinonylmethane Dyes On the Reactivity of the Cyciohexyl Moiety in 2‐Chloro‐3‐[(1‐cyclohexyl‐6‐fluoro‐3‐methyl‐1 H ‐quinoxalin‐2‐ylidene)niethyl]‐1,4‐naphthoquinonc The reactive title compound ( 1a , X = F , R 1 = C 6 H 11 , R 2 =Cl) was obtained from the reaction of 1‐cyclohexyl‐6‐fluoro‐2,3‐dimethylquinoxalinium perchlorate with 2,3‐dichloro‐1,4‐naphthoquinone. Upon treatment with pyridine and acetic acid in acetone and separation of the desired naphthophenazinone 2a , an unexpected azepinoquinoxaline 4a was isolated. The structure of 4a was determined by its mass and 360‐MHz‐ 1 H‐NMR. spectra in connection with decoupling experiments.