The Structure of Dioscorine

On the other hand, two of the possible structural isomers (LXXIV, LXXV) (1 3, 1 4) of Ar,JV-dimethyl-i-butylcycloheptyIamine have been synthesized. The IR-curves were very close to those of the saturated Hofmann base CisH N none of them proved, however, to be identical with that of the base from dioscorine. Since configurations have not been taken into consideration, these data are not conclusive. Nevertheless, a new tentative formula has been suggested (84) which takes account of the formation of a C = CHg group on decarboxylation of the hydroxy acid from dioscorine, i.e., that of the c-lactone of a tropine derivative with a j8-methyl-a,/3-butenoic acid side chain in 

A more recent communication describes a somewhat different approach to the structural problem of dioscorine. Hydrogenolysis of the lactone led to a diol which on ozonolysis afforded glycolaldehyde and a hydroxy ketone. The latter underwent cleavage to acetone and another ketone, CgH sON, the IR-spectrum of which is more in accord with a five-membered than with a six-membered cyclic ketone. On this basis structure LXXVIa has been suggested for dioscorine (123). Racemic 

6-oxotropane has been synthesiz (135, 136) different from the ketone 

CsHigON obtained from dioscorine. Thus the alkaloid seems to be a 

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The evidence so far has dealt solely with the nature of the lactone but has cast no light on the nature of the basic nucleus of this alkaloid. The experimental evidence necessary for complete elucidation of the structure of dioscorine is far from complete, yet the results of exhaustive methylation are sufficient to set up a working formula. Carbon dioxide as well as water is lost when dioscorine methohydroxide is distilled (dry) in vacuum with the formation of the triply unsaturated, oily base, methyldioscoridine (248). Methyldioscoridine no longer exhibits lactonic properties and molecular refraction measurements indicate that the three double bonds are... 

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