Alkaloids of Adenocarpus spp

Adenocarpine is split by acid hydrolysis into cinnamic acid and a basic product CioHigNj which on catalytic hydrogenation takes up 1 mole of hydrogen and gives rise to racemic o/3 -dipiperidyl. When, however, this last base is prepared by hydrogenation of adenocarpine and hydrolysis of the product, the levo form is obtained. Adenocarpine is, therefore, an AT-ciimamyltetrahydroanabasine (105). 

Orensine (C19H24ON2), m.p. 82-83°, forms a hydrochloride, m.p. 208-210° (anhydrous), a hydriodide monohydrate, m.p. 133-134°, and a picrate, m.p. 210-211°. It is optically inactive and is the racemic form of adenocarpine. When oxidized with chromic acid orensine gives a substance CiiHig04N2, m.p. 227°, which on hydrolysis with acid is split into oxalic acid and a diamine C9H4gON2 isolated as the dihydrochloride, 

When hydrolyzed with acid santiaguine produces a-truxilic acid and a base CioHigNj which is hydrogenated catalytically to ajS -dipiperidyl. Consequently, the alkaloid is W,W -o-truxil-bis (tetrahydro-anabasine), and Costa and Bibas (110) have assigned to it the partial structure CCXV. 

It has now been demonstrated that carpaine, which was previously assumed to be a pyrrolidine derivative, is actually a piperidine alkaloid. The key to the skeleton previously suggested was provided by a nitrogen-free hydroxy acid of probable composition C14H28O3, m.p. 20-25°, isolated from carpaine by a two-stage Hofmann degradation, followed by hydrogenation and hydrolysis (111). Rapoport and Baldridge (112) 

Carpaine can be methylated with formaldehyde and formic acid to JV-methylcarpaine, m.p. 84°. Since the hydroxyl group is resistant to dehydration and is readily replaced by chlorine and since the ethyl ester fails to epimerize, the 3-OH group of carpamic acid is assumed to have the equatorial configuration (115). 

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