Fischer Indolization and Its Related Compounds. XVIII. Formation of Four Unexpected Angular Benz [e] indoles on Fischer Indolization of Ethyl Phenylpyruvate 2-[(1, 4-Dimethoxy-2-naphthyl) hydrazone]

• Published in: Chemical & pharmaceutical bulletin Vol. 31; no. 12; pp. 4391 - 4400
• Main Authors: IKEDA, NISABURO, YASUDA, ZENKICHI, MITSUI, HIDEKI, ISHII, HISASHI, MURAKAMI, YASUOKI, WATANABE, TOSHIKO, SUZUKI, HIDEHARU, TANI, SHOHEI
• Format: Journal Article
• Language: English
• Published: The Pharmaceutical Society of Japan 25.12.1983; 公益社団法人日本薬学会
• Subjects: 1, 4-dimethoxy-2-naphthylhydrazone; anti-viral activity; benz [e] indole; ethanolic hydrogen chloride; Fischer indolization; formation of o-quinone; oxidation with chromic acid
• ISSN: 0009-2363; 1347-5223
• DOI: 10.1248/cpb.31.4391

The Fischer indolization of ethyl phenylpyruvate 2-[(1, 4-dimethoxy-2-naphthyl) hydrazone] (2) with ethanolic hydrogen chloride gave four angular benz [e] indole products (ethyl 4-chloro-5-ethoxy-(14a), ethyl 4-chloro-5-methoxy-(14b), ethyl 5-ethoxy-(14c), and ethyl 5-methoxy-(14d)-1-phenyl-3H-benz [e] indole-2-carboxylates), instead of the anticipated linear benz [f] indole, ethyl 4, 9-dimethoxy-3-phenyl-1H-benz [f] indole-2-carboxylate (3). Oxidation of these benz [e] indole derivatives (14b and 14d) with chromic acid in acetic acid provided an o-quinone derivative (15) which showed anti-viral activity in a preliminary biological test.