Aporphinoid Alkaloids

The year under review has witnessed a particularly bountiful harvest of new aporphine alkaloids. These, with their botanical sources, are given below. 

Laurelia philippiana Looser Alseodaphne semicarpifoHa Nees 

Guinaudeau, M. Leboeuf, A. Ramahatra, and J. Razafindrazaka, Planta Medica, 1978, 33, 243. 

Of particular interest is calycinine, which possesses a meta substitution pattern in ring D, and fuseine, which is the first simple lactam known in the aporphine series. A complete X-ray analysis was carried out on the 7V,0-diacetyl derivative of 4-hydroxynornantenine to confirm its stereochemistry and absolute configuration. The stereochemical assignments for all 4-hydroxylated apor-phines are, therefore, predicated upon this X-ray study. 

Known aporphines that have been re-isolated from natural sources are shown in Table 

A useful and timely supplementary listing of new aporphines, oxoaporphines, phenanthrenes, and 4,5-dioxoaporphines has appeared.1 The alkaloids of Glaucium species, which include several aporphines and oxoaporphines, have been tabulated2 and a general discussion of the chemistry and biogenesis of isoquinoline alkaloids, including the aporphines, has been presented.3 

Pronuciferine (1) has been synthesized by photocyclization of the brominated phenol (2).9a The light-induced rearrangement of proaporphines yields aporphines that are substituted at C-9 or at both C-8 and C-9.5 This topic is further discussed below, under the sections on aporphines and aporphine dimers. The known alkaloid N-methylcrotsparine has been found in Pachygone ovata.9b 

The year under review has witnessed the isolation and structural elucidation of no less than nine new aporphines, as well as of five aporphine-benzylisoquinoline dimers. Two of these five aporphine-benzylisoquinolines, namely kalashine and khyberine, are the first such dimers known to be substituted at C-l 1 of the aporphine moiety. Thallium(m) trifluoroacetate is an oxidizing agent which effects the cyclization of tetrahydrobenzylisoquinolines to aporphines in satisfactory yields.1 A listing of aporphinoid alkaloids has appeared.2 

The new proaporphine iso-oridine (1), isomeric with the known oridine (2), has been isolated from Papaver oreophilum.3 The supporting structural data include l3C n.m.r. spectroscopy. A-Acetylstepharine (3) has been found for the first time as a natural compound in Stephania sasakii.4 

Israilov, S. U. Karimova, M. S. Yunusov, and S. Yu. Yunusov, Khim. Prir. Soedin., 1980, 279 I Chem. Natural Compd. (Engl. Transl.), 1980, 16, 1971. 

Known proaporphines that have been reisolated from plants are  

The tetrahydrobenzylisoquinolines ( )-norcoclaurine, (i)-coclaurine, and ( )-N-methylcoclaurine can act as precursors to the proaporphine N-methylcrotsparine. 

---

The aporphinoid alkaloid PO-3 (129) was also prepared by intermolecular benzyne cycloaddition between 1-methylene isoquinolines 148 and arynes derived from 147 (Scheme 53). The alkaloid was finally isolated by means of preparative thin layer chromatography (91JOC2984). 

H. Guinaudeau, M. Leboeuf, and A. Cav6, J. Nat. Prod. 47,565 (1984). Dimeric aporphinoid alkaloids. Cites 23 new dimeric alkaloids and 8 related synthetic derivatives for 1979-1984 48 references. 

M. Shamma and H. Guinaudeau, Tetrahedron 40, 479S (1984). Biosynthesis of aporphinoid alkaloids. In addition to monomeric alkaloids, discusses proaporphine- and aporphine-benzyliso-quinoline dimers, dimeric oxidized aporphines, and types derived by catabolism of benzyliso-quinoline-derived dimers. 

---