Alangiside structure

The structure of the monoterpenoid alkaloid alangiside (115 R = H) has been confirmed by synthesis of the O-methyl ether (115 R = Me) from secologanin and 3-hydroxy-4-methoxyphenethylamine 202 the isolation of loganic acid from the same plant (Alangium lamarckii) is consistent with biosynthetic theory. 

Details have appeared of the isolation and structural elucidation of alangiside (174 R = Me, = H) (c/. Vol. 3). The location of the free phenolic hydroxy-group is based on the non-identity of the alkaloid with a sample of its isomer (174 R = H, R = Me) synthesized from secologanin/ ... 

To distinguish between these structures, a synthesis of alangiside was undertaken. Attempted condensation of 4-hydroxy-3-methoxyphenyl-ethylamine with secologanin under a variety of conditions was not successful. However, 3-hydroxy-4-methoxyphenylethylamine condensed smoothly with secologanin at pH 5.2 to afford 33 and 34. No attempts were made to obtain the individual epimers in a pure form, and the crude mixture was treated with a solution of sodium carbonate when mainly the 5/8 epimer (26) which differed from alangiside was obtained, and this on treatment with diazomethane afforded O-methylalangiside. The phenolic hydroxyl of alangiside was thus located at C-7, and structure 25 is a complete representation of the molecule (16). 

Emetine and Related Alkaloids.—A review on the ipecac alkaloids has ap-peared. (— )-Alangiside (208) is a terpenoidal lactam recently isolated from Alangium lamarckii Thw. (Alangiaceae). The structure was proven by chemical correlation with desacetylipecoside (209) (Scheme 13). ... 

No new alkaloids in this series have been isolated. However, the structure of ankorine has been revised and that of alangiside has been established with certainty. ... 

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