Yuzurine-type alkaloids

Nine alkaloids belonging to the yuzurine group were isolated from D. macropodum and D. gracile distributed in New Guinea. The structure of yuzurine (27) was 

From the IR absorptions, daphnezomine A (37), G22H35NO3, was suggested to possess OH (3600 cm ), NH (3430 cm ), and carboxylate (1570 and 1390 cm ) functionalities. Detailed analysis of the H- H COSY, HOHAHA, HMQC-HOHAHA and HMBC correlations defined the gross structure of 37, consisting of an aza-adamantane core (N-1, C-1, and C-5-C-12) fused to a cyclohexane ring (C-l-C-5 and C-8) and another cyclohexane ring (C-9-C-11 and C-15-C-17), and three substituents at C-2, C-5, and C-8 [44]. 

In order to determine the absolute configurations of 37 and 38, a crystal of the hydrobromide of 38 generated from MeOH/acetone (1 9) was submitted to X-ray crystallographic analysis [44]. The crystal structure containing the absolute 

Daphnezomines C (39) and D (40), possess the secodaphniphylline-type skeleton with a nitrone functionality, while daphnezomine E (41) is the first N-oxide of a daphniphylline-type alkaloid, though the N-oxides of several yuzurimine-type alkaloids have been reported [45]. 

Spectral investigations of daphnezomines F (42) and G (43), whose molecular formulas are C27H35NO8 and C27H35NO7, respectively, revealed that they are structurally related and possess a l-azabicydo[5.2.2]undecane moiety. The conformation of the l-azabicyclo[5.2.2]undecane ring in 43 was elucidated by a low-temperature NMR study and computational analysis [46], 

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