Copyrines

S. Liu, B. Oguntimein, C.D. Hufford, and A.M. Clark, 3-Methoxysampangine, a novel antifungal copyrine alkaloid from Cleistopholis patens, Antimicrob. Agents Chemother., 34, 529, 1990. 

These compounds have also been called pyridopyridines and benzodiazines. The early literature describes 1,5-naphthyridine as isonaphthyridine and the 1,6-isomer as 2,6-naphthyridine. Prior to 1950, the 2,7-naphthyridines were referred to as derivatives of copyrine. Fortunately, the nomenclature has now been standardized and much of the confusion has been eliminated. 

Although a substantial number of papers are devoted, at least in part, to 2, 7-naphthyridines, the spread of information is quite unbalanced in favor of primary syntheses. Accordingly, the 2,7-naphthyridine system will be covered in a single chapter. Several reviews of naphthyridine chemistry include material on the 2,7-system.49 50 53 61 265 407 456 1357 1430 1432 The original system name, copyrin/ copyrine,13 cf 39,40 is still used occasionally. 

The six possible pyridopyridine systems have been known almost universally since circa 1930 as 1,5- (1), 1,6- (2), 1,7- (3), 1,8- (4), 2,6- (5), and 2,7-naphthyridine (6), However, the occasional use of an appropriate pyridopyridine or diazanaphthalene may still be found in some publications, Historically, the word naphthyridin(e) was coined by Arnold Reissert in 1893 specifically for the 1,8-naphthyridine system (4) and was so used for some years, especially in the German literature. Other terms, such as isonaphthyridine [for 1,5-naphthyridine (1)], benzodiazines (very misleading), pyridinopyridines , 2,5-naphthyridine [for 1,6-naphthyridine (2)], and copyrin(e) 13,40 or copurine39 [for 2,7-naphthyridine (6)] have appeared in the literature. 

Condensations with /7-diketoneg Copyrine and pyrazole ring closure... 

Sampangine (XIV. 187) and 3-methoxysampangine (XIV.144) were isolated from Duguetia hadrantha, this is the first report of the cooccurrence of the copyrine-type alkaloids from a Duguetia species. These compounds were isolated previously from C. odorata of Asian and Cleistopholis patens of African origin, respectively. 

---