Hydroxymethyl groups, rotational positions

The structures of V - and V -amylose are similar. In both cases the amylose chains form left-handed helices pack in an antiparallel manner in the space group V -amylose i " was originally believed to have a sixfold helical conformation but further refinement has shown only twofold symmetry due to different rotational positions of glucose hydroxymethyl groups. The structure contains significant amounts of water. This refinement locates these guest molecules in interstitial sites between neighbouring helices of amylose... 

The most unusual feature of the alkaloid laburnine is that it belongs to the lupin alkaloid family due to its source and to the Senecio alkaloid family (324) due to its constitution as a derivative of pyrrolizidine (CXXXVIII) rather than quinolizidine (I). The preferred position of attachment of the CHjOH-group on the pyrrolizidine nucleus in laburnine is C-1 (CXXXIX), since Galinovsky and his coworkers (313) pointed out that Men shikov s trachelanthamidine (known to be a 1-hydroxymethyl-pyrrolizidine) (325) and their laburnine were probably optical antipodes. The properties of the derivatives of the two compounds are similar and the optical rotations are approximately equal and opposite. 

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