Araliopsis

Furoquinoline Alkaloids.—Well-known furoquinoline alkaloids have been identified for the first time in twelve species of the Rutaceae (see the Table 2.5.8,9,11—13,15,16 on p an(j rare trimethoxydictamnine halfordinine (1 R1 = R2 = R3 = OMe) has been obtained from Araliopsis tabouensis2 and from Teclea verdoorniana.12 The isolation of y-fagarine and skimmianine from Tylophora asthmatica (Asclepiadaceae)14 and skimmianine from Datura stramonium (Solanaceae)4 is of considerable taxonomic interest. 

The major alkaloid of Araliopsis tabouensis is (+)-N-methylplatydesminium salt (see Vol. 6), and a study of the minor constituents has now resulted in the isolation of (+)-isoplatydesmine (2) and the pyranoquinolone (+)-ribalinine (folifine) (3).2... 

The hydroxydihydropyranoquinolone (—)-ribalinine (47) is a constituent of the trunk and root bark of Araliopsis soyauxii f the (+ )-enantiomer (folifine) was obtained earlier from Haplophyllum species and the racemate, which has been synthesized was isolated from B. riedelianum. (-l-)-Isoplatydesmine (43) has also been isolated from A. soyauxii and can be regarded as a new alkaloid since isoplatydesmine obtained recently from Pelea barbigera (cf. Vol. 6) probably is the... 

Skimmianine Aegle, °° Araliopsis,Datura, Dictamnus, Esenbeckia,Euxylophora, ... 

Araliopsine (62), which is present in Araliopsis soyauxii (J. Vaquette et al., Phytochem., 1975, 15, 743) and Zanthoxyllum simulans (z. Chang et al., Yaoxuc Xuebao, 1981, 16, 394 C.A., 1982, 97, 20735) has been synthesised by G.M. Coppola (J. heterocyclic Chem.,1983, 1589) by reacting N-methylisatoic anhydride with the lithium enolate (51) and treatment of the intermediate epoxide with acid. 

N-Methylplatdesminium salt (90) is also present in Araliopsis tabonensis (P.G. Waterman, Biochemical Systematics, 1973, 1, 153). 

The same enantiomer occurs in Araliopsis tabouensis Aubrev et Pellegr. (45), and (—)-ribalinine has been found in the root bark of A. soyauxii Engl. (44). 

A quaternary alkaloid extracted by Boyd and Grundon (37) from leaves of Skimmia japonica Thunb. was shown to be the (+)-A/-methyl-platydesminium salt (51) by comparison with the racemate that had been synthesized earlier (27). The alkaloid has subsequently been isolated from Ruta graveolens (39) and from Araliopsis tabouensis (66). 

When heated briefly above its melting point, (+)-N-methyl-platydesminium iodide gave the 4-quinolone 52, [a]D + 82° (MeOH) (37), identified by comparison with the synthetic racemate (27). Higa and Scheuer (43) have now isolated from Pelea barbigera (Gray) Hillebrand quinolone 52, named isoplatydesmine. Araliopsis soyauxii has been shown to contain (+)-isoplatydesmine as the major alkaloid of the root bark (44) the same enantiomer is a constituent of A. tabouensis (45). 

Araliopsis soyauxii (Section III,C,3) thus has the (R) configuration, assuming that the rearrangement reaction follows the same stereochemical pathway as the balfourodine-(//-balfourodine transformation. 

Dimers produced by Diels-Alder reactions between py-ranoquinolone and dihydrofuroquinolone alkaloids occur in a number of rutaceous species. These compounds are known from Araliopsis, Euxylophora, Geijera, Oricia, Ptelea, and Vepris (Waterman, 1986). 

Halfordinine I 4,6,7,8-tetraOMe Araliopsis tabouensis [44], Diphasia angolensis [44], Halfordia scleroxyla [44], Melicope leptococca [18], M. perspicuinervia [44], Nematolepis phebalioides [28], Oricia suaveolens [44], Sarcomelicope argyrophylla [21], Teclea verdoorniana [44]... 

---