Ibogamine-Cleavamine Group

Catharanthine—Ibogamine-Cleavamine Group. Catharanthine is one of the alkaloids produced in suspension cultures of the 200 GW cell line of Catharanthus roseus, 2a and ibogamine has been found in the stem and root bark of Hazunta modesta var. modesta subvar. montana.62 Four Ervatamia species have been shown to contain several alkaloids of this group.64 Thus, E. orientalis (R. Brown) Domin contains voacangine, conopharyngine, pandine, and pandoline, E. daemeliana 

Domin contains voacangine, conopharyngine, and iboxygaine, E. obtusiuscula Mgf. contains coronaridine, isovoacangine, and a trace of epipandoline, while E. lifuana Boiteau has yielded pandine, pandoline, epipandoline, conopharyngine, and traces of coronaridine, and voacangine. 

Other extractions have yielded isovoacristine from leaves of Tabernaemontana heyneana, and its presence has been detected in the leaves and flowers of T. coronaria, both of Indian origin.114 

A new alkaloid, 3-hydroxycoronaridine, has been found in Tabernaemontana glandulosa Stapf 115 its structure was deduced from its spectra, particularly its mass spectrum, and confirmed by reduction with sodium borohydride, which gave coronaridine (240). The stems of a related species, T. flavicans, collected in Peru, contain ibophyllidine and ibophyllidine N-oxide.116 

Three recent communications are concerned with the alkaloids of T. albiflora (Miq.) Pull., endemic to French Guyana.117 Seven new alkaloids have been isolated these include albifloranine (247),1170 (+)-19-hydroxy-20-epi-pandoline (248), (+)-(20R)-18,19-dihydroxypseudovincadifformine (249),1176 19-hydroxy- 

Kalaus, K. Nogradi, and C. Szantay, Acta Chim. Acad. Sci. Hung., 1979, 99, 73. 

Heyneatine is a carbinolamine ether of a new type, in which the oxygen atom is situated between C-3 and C-19 (n.m.r. spectrum). Since reduction (with LiAlH4) gives rise to (19S)-voacangarinol or (with NaBH4) to (19S)-voacangarine, the complete structure of (—)-heyneatine must be (167).81 

Reference has been made above to the determination of the stereochemistry at C-7 of cleavamine 7-chloroindolenine.88 

Details of the syntheses, by Harley-Mason and his collaborators, of ( )-16-hydroxydihydrocleavamine,107a ( )-a- and ( )-j3-dihydrocleavamines, ( )-methoxycarbonyldihydrocleavamine, ( )-coronaridine, ( )-dihydrocatharan-thine, ( )-ibogamine, ( )-epi-ibogamine, and ( )-catharanthine have now been published.107  

Kunesch, J. Poisson, and C. Moretti, Communication au Colloque Substances Naturelles d Interet Biologique du Pacifique , Noumea (New Caledonia), August, 1979 quoted in ref. 104. 

Further investigations into the constituents of Tabemaemontana apoda Wr. ex Sauv. Peschiera apoda Mgf.) have revealed the presence of voacangine hydr- 

In connection with total synthesis in this subgroup, mention may be made of a model synthesis of 5-oxodesethylcatharanthine (242) by the photocyclization of the chloro-amide (243). Extension of this approach to the synthesis of catharanthine is at present being hindered by the non-availability of the dihydropyridine derivative required for the preparation of the 20-ethyl analogue of (243). 

Reagents i, CH2=CHCHO, BF3-Et20 ii, tryptamine, NaBH4 iii, [PiKPPhj), MeCN, at 70 C iv, [(MeCN)2PdCl2], AgBp4. then NaBH4 

---

Aspidospermine-Aspidofractine-Eburnamine Group Ibogamine-Cleavamine Group... 

Ibogamine-Cleavamine Group. Voacangine has been isolated from Pandaca retusa seeds and leaves and trunk bark and from Voacanga thouarsii. The seeds of Pandaca retusa also have coronaridine, the leaves and bark also... 

Ibogamine-Cleavamine Group. Another " synthesis of ( )-velbanamine and (+ )-isovelbanamine has been reported in which a precursor (81) having the five rings of the pentacyclic ibogamine type is cleaved between C-16 and C-21. 

Catharanthine-Ibogamine-Cleavamine Group. The chemistry and pharmacology of alkaloids of Tabernanthe iboga have been reviewed." New extractions have resulted in the isolation of coronaridine (previously observed), voacangine, isovoacangine, and ibogamine from the bark of Ervatamia coronaria, coronaridine and 19-oxocoronaridine from the roots of Tabernaemontana... 

---