Makomakine and Mokonine, New Indole Alkaloids from Aristoteria serrata

A key intermediate, makomakine (I), involved in the proposed scheme of biosynthesis1° of the Aristotelia alkaloids, has been isolated from an A. sermta extract, together with makonine ( 1 0 , a dehydroaristotelinone.A number of novel indole alkaloids occur in the New Zealand elaeocarpaceous plant Aristotelia serrata W.R.B. Oliver (Maori name: makomako) ,1'2'3 and in other Aristotelia spp. 4,5,6,7,8,9A possible mode of biogenesis of these alkaloids has been put forwardlo involving the hypothetical key intermediate (I).We report the isolation in small amount of a base,m.p. 99-loo', [ a ] : (+I 131.2" (c 0.5, CHCl ), from A. serrata whose structure is shown to correspond with (I).This base, 3 for which the name makomakine is suggested, has an indole nucleus from its U.V. spectrum; its ' H and 13c n.m.r.spectra show that it has one double bond in a vinylidine group, and from its molecular formula C20H26N2 it must thus have two ring systems in addition to the indole nucleus.