Improved antitumor activity by modification of nogalamycin.

Nogalamycin, an antitumor antibiotic, has been converted to a series of analogs by removal of the carbomethoxy group at C-10 and replacement of the neutral sugar at C-7 by other groups. Removal of the carbomethoxy group to give disnogamycin (6) followed by acidic alcoholysis gave pairs of isomeric 7-alkoxy compounds differing in configuration at C-7. Treatment of 6 with trifluoroacetic acid followed by nucleophiles gave a series of analogs having substituents at C-7 with a configuration at C-7 opposite to that of nogalamycin. Among the analogs prepared, 7-con-O-methylnogarol (7) is a highly active antitumor agent.