New furoquinoline and dihydrofuroquinoline alkaloids

Tecleaverdoorine, which is found in the stem bark of Teolea verdoorniana, has the structure (65). The failure of this alkaloid to afford a chroman derivative on acid treatment eliminates other alternative formulations in which the prenyl group and the phenolic hydroxyl group are ortho to one another (J.I. Okogun and J.F. Ayafor, J.chem.Soc., Chem.Comm., 1977, 552). This alkaloid may be 

Tecleine, first obtained from T. sudanica (R.R. Paris and A. Stambouli, C.rend.Med.Scl., 1959, MS, 3736), is likely to have the constitution (57) since it gives the known alkaloid flinderslamlne (68) on methylation. It is also present in T. verdooniana (Ayafor and Okogun, loc.clt.). Another alkaloid from this species is tecleamlne (69) (Ayafor et al., Phytochem., 1982, 21, 2603). 

Delbine, m.p. 229-231 °C and montrifoline, m.p.2i(5-2il7°C are new furoquinollne alkaloids tram Monnieria trifoliata. The former yields kokusaginine (70) on methylation with diazomethane, and is thus a hydroxymethoxydictamnine. Since it is not Identical with helipavlfoline (71) delbine is considered to be 6-hydroxy-7-methoxydictamnine (72). 

Montrifoline is converted into delbine by fusion with alkali and, as it is not the same as evolatine (73), it is assigned structure (7 ) (J. Battacharyya and L.M. Serur, Heterocycles, 1981, 16, 37I). 

Heliparvifoline, m.p. 245 247°C, is metabolised by Haplophyllum parvifolia (P.T.O. Chang et al, J.pharm.Sci., 1976, 65, 561). On 0-methylation it too forms kokusaginine and was considered to be 7-hydroxy-6-methoxydictamnine. This conclusion is now confirmed by a synthesis (T. Sekiba, Bull.chem.Soc.Japan, 1978, 51, 325). 

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