Proximity effects in diaryl derivatives. Part V. Syntheses of 2,7-and 2,8-dichlorophenoxazine derivatives. Smiles rearrangements activated only by halogen substituents

Abstract

Syntheses of N-benzyl-2,7-dichlorophenoxazine and 2,8-dichlorophenoxazine show that the dichlorophenoxazine obtained² by reduction of 4,4′-dichloro-2,2′-dinitrodiphenyl ether with lithium aluminium hydride is the 2,8-isomer. The formation of this compound, therefore, does not involve a Smiles rearrangement. Reaction of 2′-benzylamino-2,4′,5-trichlorodiphenyl ether with potassium carbonate in dimethylformamide results in Smiles rearrangement to N-benzyl-2,8-dichlorophenoxazine, although the ring subject to nucleophilic attack is activated only by halogen substituents.