1961 年 81 巻 7 号 p. 1033-1036
6-Cyanophenanthridine (I) is derived to 6-cyanophenanthridine 5-oxide (II) by treatment with hydrogen peroxide (100°) in glacial acetic acid but to phenanthridine-6-carboxamide (III) by treatment with hydrogen peroxide (room temperature) in alkaline medium. 6-Phenanthridinecarboxamide 5-oxide (IV) is formed from (III) by the former conditions and from (II) by the latter conditions. (III) and (IV) are also obtained by respective hydrolysis of (I) and (II) with 90% sulfuric acid (cf. Chart 1). The carboxamide group in (III) and (IV) so produced differs somewhat in the two compounds. (III) changes into 6-phenanthridinecarboxylic acid (V) by treatment with nitrous acid while (IV) remains inert to this treatment. The Hofmann reaction of (III) affords 6-aminophenanthridine (VI) while (IV) is resistant to this reaction and forms 6-aminophenanthridine 5-oxide (VII) in a small yield, with almost 50% recovery of the starting compound (Chart 2). There is a possibility that a cyclic structure involving hydrogen bonding would be formed between -CONH2 and N-O groups in (IV), as shown in Chart 3, and this might be one of the reasons for resistance of this compound to the foregoing reaction. Treatment of (V) with hydrogen peroxide in glacial acetic acid failed to produce the anticipated 6-phenanthridinecarboxylic acid 5-oxide (VIII) and phenanthridone (IX) and 6-hydroxyphenanthridine 5-oxide (X) were formed (Chart 4). It should be added that (VI) can easily be prepared by heating 6-phenoxyphenan-thridine with urea.