Peripentadenia mearsii, alkaloids

Peripentadenia is a monotypic genus of the family Elaeocarpaceae represented by Peripentadenia mearsii (C. T. White) L. S. Smith, a tree growing in rain forests of northern Queensland. Besides unidentified minor alkaloids, the species yields one major alkaloid, peripentadenine (49) (87). Its molecular formula, C22H34N203, was established by high-resolution mass spectroscopy the presence of phenol, ketone, secondary amide, and tertiary amine functionalities was deduced from examination of spectroscopic data. 

Mearsine (336) was isolated as a minor alkaloid of Peripentadenia mearsii [703]. Its structure was determined with elemental analysis of the crystalline picrate, MS, IR, UV, and 13C NMR, diacetylation of the NaBH4 reduction product, and X-ray crystallography [703,704]. The structure was confirmed by synthesis of (+)-336 from (-)-5-methyl-2-cyclohexenone via a Mannich reaction [705]. The structure of 336 suggested its biosynthesis was from acetate via a polyketide pathway [703]. 

Three tropane alkaloids, two of which are new, have been isolated from the leaves of a tree belonging to the Queensland species Peripentadenia mearsii (C. T. White) L. S. Smith, (fam. Euphorbiaceae). The two new alkaloids are ( + )-(3R,6/ )-3a-acetoxy-6)S-hydroxytropane (1) and ( + )-2a-benzoyloxy-3/3-hydroxynortropane (2) (relative configuration only is shown here) the known alkaloid is 3 -benzoyloxytropane (3). 

Figure 22 Alkaloids of Elaeocarpus fuscoides, °° Peripentadenia mearsii and Elaeocar-pus sphaericu ° isoelaeocarpicine (860) isoelaeocarpine (861) elaeocarpine (862) elaeocarpenine (863) mearsamine (864) 3-oxoisoelaeocarpine (865) elaeocarpine A/-oxide (866).

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