Psychotridine, the major alkaloid from Psychotria beccarioides Wernh. has the molecular composition C55H62N10. It has been shown to be related to hodgkinsine, and a structure (4) derived from five Nb-methyltryptamine units is proposed. Mass spectral evidence for the structure is supported by the conversion of psychotridine through a pentamethiodide into a penta-indolenine base, analogous to the tri-indolenine base derived from hodgkinsine Nb,Nb',Nb?-trimethiodide. The structure is also supported by comparison of the 13C N.M.R. spectra of hodgkinsine and psychotridine.
A new alkaloid isolated from Euphorbia atoto Forst. has been shown to be (+)-9-aza-1 -methylbicyclo[3,3,1]nonan-3-one.
Examination of the tertiary base fraction from Alstonia spectabilis R.Br. has led to the isolation of villalstonine, macralstonidine, vincamajine, quebrachidine, pleiocarpamine, and AT(,)-methylsarpagine. Pleiocarpamine, which is a constituent of Pleiocarpa mutica Benth. and Hunteria eburnea Pichon,l and N(,,-methylsarpagine have been obtained previously as hydrolysis products respectively of the bis-indoles villalstonine and macralstonidine. Drastic conditions are required for the hydrolysis of these bis-indoles, and it is unlikely that a significant amount of hydrolysis would have occurred during the isolation of the alkaloids. N(,)-3Ietliylsarpagine has not previously been isolated directly from natural sources but the quaternary N(b)-metho salt has been isolated from Pleiocarpa mutica.2 The occurrence of vincamajine and of esters of both vincamajine and quebrachidine in Alstonia constricts were recently reported.3 From another Kew Guinea species, Alstonia glabriflora Mgf., the alkaloids villalstonine, macralstonine, pleiocarpamine, and alstophylline have been isolated. Alstophylline, which has been isolated previously as an hydrolysis product of macralstonine and as an alkaloid from Alstonia macrophylla Wall.,4 is one of the major constituents of the tertiary base fraction of A. glabriflora. Experimental (a) Alkaloids from Alstonia spectabilis Bark of Alstonia spectabilis R.Br. (Herbarium voucher number, Hoogland 5138) was collected by Dr R. Hoogland in the southwestern foothills of the Finisterre Mountains in New Guinea. The milled, dried bark (1090 g) was extracted with methanol, and the acidified concentrate diluted with water and defatted by extraction with light petroleum. The concentrate was basified (NH3) and extracted repeatedly with diethyl ether to give 4.8 g tertiary bases. Extraction with chloroform then gave a further 7.0 g tertiary bases. Thn more intractable material extracted by
Although available in only very small quantities, two minor alkaloids from the shrub Boehmeria platyphylla Don. are of special interest because so little is known of alkaloids from the family Urticaceae, and because of their biosynthetic relationship to the phenanthroindolizidine alkaloids of Tylophora and Picus species1 and even closer relationship to the alkaloids of the botanically unrelated tree Cryptocarya pleurosperrna White & Francis (family Lauraceae).2-4 Consideration of the structures of the three Boehrneria alkaloids provides further evidence for the postulated biosynthetic scheme135 whereby cryptopleurine and the Tylophora bases are derived from two equivalents of dihydroxyphenylalanine and one equivalent of lysine or ornithine respectively. Each of the three alkaloids corresponds t o a different stage of the biosynthetic scheme.It was shown in Part 1 6 that the major B. platyphylla alkaloid is 3,4-dimethoxyw-(2'-piperidy1)acetophenone (Ia), and its structure was established from its preparation by 0-methylation of pleurospermine (Ib), an alkaloid from the leaves of Cryptocarya ple~rosperma.~ One of the minor B. platyphylla alkaloids, C24H27N03, m.p. 197-198", -64" in chloroform, can also be directly related to a C. pleurosperma alkaloid, as, apart from a difference in the magnitude of [ N I D , it is identical with cryptopleurine (11), the highly vesicant alkaloid from the bark of C. pleuros~e r r n a .~ Purified (-)-cryptopleurine was found to have [ & I D -109" in chloroform, in agreement with the previously reported value of -106",3 so that it is evident that cryptopleurine is obtained from B. platyphylla as a partial racemate.The second minor base, C24H2$$O3, m.p. 134.5-135.5", +4.6" in chloroform, has a strong molecular ion peak a t mle 379 (89% of base peak), two mass units higher than that observed in the mass spectrum of cryptopleurine. As there was
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