2-Chloro-10- phenoxazin

Treatment of 2-amino-3-hydroxypyridine (185) with 2-chloro-3-nitropyridine (193) easily provided intermediate 194. Attempts to cyclize 194 with potassium hydroxide in aqueous ethanolic solutions failed, probably due to strong H-bonding. Similarly as with phenoxazines, the cyclization smoothly proceeded in DMSO to give low yield (31%) of 1,9-diazaphenoxazine (195) (Scheme 30) (74CC878, 76JHC107, 77H391). 

Phenoxazin-3-ones and phenothiazin-3-ones can be prepared by condensation of 2-aminophenols or -thiols with quinones. Alizarin Green G (61), for example, is obtained from (59) and (60). Similarly, 2-aminothiophenols and 6-chloro-2-methoxy-l,4-benzoquinone (62) afford phenothiazin-3-ones (63). 

An extension of this synthetic route to alkyl-substituted o-amino-phenols gave symmetrically substituted dialkyl phenoxazines, but chloro- and methoxy-substituted o-aminophenols failed to react under similar conditions. 4-Methyl- (or 4-ethyl-)2-aminophenol, by reaction with the corresponding hydrochloride, yielded 2,8-dimethyl-and 2,8-diethylphenoxazine, respectively.8... 

Bromo-aryl ether 46 (Scheme 18), on treatment with one equivalent of sodium amide in boiling benzene, underwent rearrangement into 47 in 92% yield. The presence of an N-alkyl substituent on the anihne nitrogen atom was essential for the rearrangement. Flowever, 46 heated with potassium carbonate in dimethylformamide afforded 2-chloro-lO-(3-dimethylaminopropyl)phenoxazine 48 in 90% yield [33]. It was later proved [34] that the cyclization of 46 into 48 involves the rearrangement via 47. Rearrangements of orfho-aminodiphenyl ethers have been reviewed [35]. 

Figure 2.12. MALDI mass spectrum of 2-chloro-10-(6-chlorohexyl)-10H-phenoxazine (MW = 335 Da). The ion of miz 284.70 is due to cetrimonium bromide.

D-00561 3-[(5-Chloro-2-hydroxy-3- 22521-79-5 V-(4-Ethoxyphenyl)-2-hydroxyacetamide, in E-00051 22914-89-2 l,7,9-Trihydroxy-3//-phenoxazin-3-one, T-00308... 

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