Phenanthridine-5-oxide

Irradiation of phenanthridine 5-oxides gives complex mixtures containing dibenzoxazepines. The reaction is solvent dependent. In benzene, for example, 6-phenylphenanthridine 5-oxide affords the dibenzoxazepine 4a (26%), 6-phenylphenanthridine (12%), 5-phenylphenanthrid-6(5//)-one (19%) and (V-benzoyl-2-(2-hydroxyphenyl)aniline (7%).27... 

Phenanthridine (74) was converted by NBS into the 2-bromo derivative (40%) (55JA6379), but the bromine-sulfuric acid-silver sulfate reagent gave low yields of 1-, 4-, and 10-bromophenanthridines in the ratio (1 6.4 9.5), a reactivity order which contrasts with that found in nitration (1 > 10 > 4 > 2) (69AJC1105). Phosphoryl chloride converted phenanthridine 5-oxide into the 6-chloro derivative, but when that position was blocked by a phenyl substituent, the reductive chlorination process gave a 2-chloro compound (84MI2). 

Quinoline 1-oxide undergoes nucleophilic attack by ozone to yield a hydroxamic acid (128), and 40% of the starting iV-oxide is recovered (Scheme 74). When an excess of ozone is employed the aldehydes (129) and (130) are obtained. Formation of these products has been attributed to electrophilic attack by ozone rather than further oxidation of (128), because in a separate experiment (128) yielded carbostyril on treatment with ozone. Isoquinoline 2-oxide yields 2-hydroxyisoquinolin-l-one, and acridine 10-oxide gives 10-hydroxyacridone and acridone in a similar manner to the above. Likewise, phenanthridine 5-oxide affords mainly 5-hydroxyphenanthridone. Quinoline 1-oxide undergoes oxidation by lead tetraacetate as shown (Scheme 75). 

Similar transformations have been reported for quinoline 1-oxide and 3-, 4-, 5-, 6-, 7-, and 8-methylquinoline 1-oxides in aqueous solution,151 for quinoxaline 1-oxide,152 for adenine 1-oxide,153 and for phenanthridine 5-oxide (181 R = H) which yields phenanthridone (182 R = H).154... 

The reaction between phenanthridine-5-oxide and ethyl acrylate takes an entirely different course leading to the isoxazolidine (217), and then to ethyl l-hydroxy-2-(6-phenanthridinyl)propionate.307... 

The formation of the adduct (218) from phenanthridine-5-oxide and dimethylketene in benzene is accompanied by deoxygenation... 

Methylphenanthridone is formed from the reaction of either phenanthridine-5-oxide or 5-... 

Phenanthridine 5-oxide cation Phenanthridin-N-oxid-Kation 44.002/40.620 H9/4... 

---