Nortropane

This small group of four representatives comprises the 3/i-hydroxytropane (40), its two naturally occurring ester derivatives 41 and 43, and the nortropane derivative 3/i-benzoyloxynortropane (42). 

The nine members of this group (76-84) are formally derived from the not yet naturally found 3a,6/ ,7/i-trihydroxytropane (vide infra, compound 170) (or from the corresponding nortropane). 

These are the group of alkaloids that possess a 8-methyl-8-aza-hicyclo [l,2,3]octane or tropane skeleton, e.g. atropine, cocaine and scopolamine. Tropane alkaloids occur mainly in plants from the families Solanaceae and Erythroxylaceae. 8-Aza-hicyclo[l,2,3]octane, i.e. tropane without the 8-methyl group, is known as nortropane. 

Goldmann, A., B. Message, D. Tepfer, R. J. Molyneux, O. Duclos, F. D. Boyer, and A. D. Elbein. Biological activities of the nortropane alkaloid, calystegine B2, and analogs structure-function relationships. J. Nat. Prod. 59 1137-1142. 

Molyneux RJ, Nash RJ and Asano N (1996) Chemistry and biological activity of the calystegines and related nortropane alkaloids. Alkaloids, Chemical and Biological Perspectives (ed Pelletier SW) Vol 11. Elsevier, Amsterdam, pp 303-343. 

A common procedure used to forge carbocyclic systems is represented by the ring-closing metathesis reactions exploiting various Grubbs-type carbene catalysts. Based on this cyclization technology, Skaanderup and Madsen [71], on the way to polyhydroxy-nortropane calystegines, reported the asymmetric synthesis of aminated 6a-carbahexoseptanose derivatives 311. 

Soulie, J. et al. General Access to Polyhydroxylated Nortropane Derivatives through Hetero Diels-Alder Cycloaddition. Part II Synthesis of ( )-Calyslegine Bi 4.2 1996 [181]... 

New 3/ -acylamino-nortropanes (19) with a variety of A—CO (aroyl, pyrimidine-carboxylic, etc.) and R (benzyl, heteroarylmethyl, etc.) groups have been synthesized as potential pharmaceutical agents.23... 

Other novel and noteworthy investigations concerning Diels-Alder reactions of nitroso dienophiles are on the one hand directed to novel accesses to these dienophiles [358] on the other hand, synthetical approaches to nortropanes [359, 360], pyrrolocastanospermine analogs [361] and novel annelated indoles [362] have been developed basing on this powerful preparative tool. 

Calystegine B4 (tetrahydroxy nortropane) Calystegine C1 (tetrahydroxy nortropane)... 

Imino-2,5,6-trideoxy-d-gulo-heptitol (imino sugar) Lentiginosine (dihydroxy indolizidine) cV-Methylcalystegine B2 (tetrahydroxy nortropane)... 

Glycosidase-inhibiting alkaloids from plants are classified into five structural classes polyhydroxylated pyrrolidines, piperidines, indolizidines, pyrrolizidines, and nortropanes. Furthermore, they also occur as the glycosides. This review describes recent studies on isolation, characterization, glycosidase inhibitory activity, and therapeutic application of the sugar-mimicking alkaloids from plants. 

Fig. 5.8 Structures of nortropanes from the Solanaceae and Convolvulaceae families.

Tab. 5.1 Distribution of polyhydroxylated nortropane and indolizidine alkaloids in the Convolvulaceae. 

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