Fifteen isoquinolone alkaloids are presently known. They may be found either in the fully aromatic form A, or else in the partially reduced form B. The numbering system is as indicated in expression A. The R substituent on the nitrogen atom may be either hydrogen or methyl, and carbons 6 and 7 usually possess oxygenated substituents. Three dimeric isoquinolone alkaloids are known; these are baluchistanamine (1), revolutinone (9), and punjabine (15).Isoquinolone alkaloids have been found among the Ranunculaceae, Menispermaceae, Berberidaceae, Papaveraceae, Hernandiaceae, Fumariaceae, Lauraceae, and Monimiaceae. The alkaloid siamine (11), found in a leguminaceous plant, has an exceptional oxygenation pattern and also bears a methyl substituent at C-3. It, thus, differs markedly from the other naturally occurring isoquinolones.Isoquinolones may originate in nature from the oxidation of benzylisoquinolines. It is possible, however, that they may also be formed from the in vivo oxidation of protoberberines, phthalideisoquinolines, or even spirobenzylisoquinolines.The biogenesis of siamine ( 11) is clearly different from that of the fourteen other isoquinolone alkaloids.Nmr chemical shifts are in values. References to nmr data that are immediately followed by a double asterisk (**) indicate that the original spectral assignments may have been slightly modified in the present listing. Chemical shifts possessing identical superscripts are interchangeable. All nmr values are at 60 MHz unless indicated otherwise. If more than one reference is cited for nmr spectral data, it is always the first reference which is the one actually quoted in the present review.Üv wave-lengths are in nm, and log e values are between parentheses. Only values for max are given, unless specifically indicated otherwise. Ir values are in cm-1. 5 4 o 1 BALUCHISTANAMINE C37H38NiOg* 638.716 2.35 s CHg-l3 Aromatic protons as multiplets centered at 6. 98, 7.38, 7.55 3 Methoxy singlets at 3.62, 3.85, and 3.90
