Die Struktur des Spermin‐Alkaloides Aphelandrin aus Aphelandra squarrosa N EES . 170. Mitteilung über organische Naturstoffe

The structure of the spermine alkaloid aphelandrine from Aphelandra squarrosa N EES The new spermine alkaloid aphelandrine ( 2 ) has been isolated from Aphelandra squarrosa N EES . By oxidation of 2 with KMnO 4 followed by methylation (CH 2 N 2 ) 12 and 14 could be prepared ( Scheme 2 ). Fusion of 2 with KOH yielded spermine ( 1 ) whereas hydrolysis of 2 in hot hydrochloric acid results in lacton 17 , the structure of which could be elucidated by comparison with a synthetically prepared model compound ( Scheme 3 ). The benzylic bonds N (10), C(11) as well as O(16), C(17) of 2 could be cleaved by hydrogenolysis (compare 23 and 26 ; Scheme 4 ). The elucidation of the correct linkage of the spermine moiety with the aromatic dicarboxylic acid is based mainly on chemical and spectroscopic evidence of the tetrahydro derivative 26 , the Hofmann ‐degradation products 28 , 30 and 31 ( Scheme 6 ) as well as the ester 35 , prepared by partial hydrolysis of 2 ( Scheme 7 ).