Castanospermine structure

Winchester BG Cenci di Bello I, Richardson AC, Nash, RJ, Fellows LE, Ramsden NG Fleet G. (1990) The structural basis of the inhibition of human glycosidases by castanospermine analogues. Biochem J 269 227-231. 

This compound exhibits the same relationship to (3-D-fructofuranose as 1-deoxy-nojirimcin does to D-glucopyranose. In 1979, a polyhydroxyindolizidine alkaloid was isolated from the poisonous fruit of Castanospermum australe, a handsome Australian indigenous tree, and coined castanospermine (8) after its source.28 A compound subsequently isolated from the seeds of this plant was the pyrrolizidine australine (9),29 also found in Alexa leiopetala,30 along with other compounds. These discoveries increasingly supported the hypothesis that imino sugars and their structural relatives might be a fairly common family of natural products, and their widespread... 

Castanospermine, a new alkaloid isolated from toxic seeds of the Australian legume Castanospermum australe, has been shown to be 8a/Tindolizidine-lcr,6/ ,7cr,8/ -tetraol (1). The structure and relative configuration were determined by X-ray crystallography.1... 

The bioactivity of castanospermine and related alkaloids continues to inspire chemists to devise new synthetic routes to the alkaloid, as well as to iimumerable structural, stereochemical and other analogs. The ensuing discussion deals only with reported syntheses of the four natural products 239-242. For syntheses of other reported stereoisomers of the indolizidine-l,6,7,8-tetraols (Fig. 4), the following references should be consulted (-)-l-epicastanosp>ermine (243) (194), ( )-7-epicastanospermine (195) and (15,6S, 75, 87f,8a7 )-7-epicastanospermine (244) (196),... 

Enantioenriched 196 was prepared by ring rearrangement metathesis (RRM) of 197. Through the agency of regio- and stereo-controlled hydroxylation reactions, (+)-castanospermine 198 and both isomers 199 of the pentahydroxylated indolizidine uniflorine-A of putative structure 200 were prepared as shown in Scheme 57 <05T8888>. 

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