Polycyclitols - Novel conduritol and carbasugar hybrids as new glycosidase inhibitors

A family of novel carbasugar analogues (bicyclitols) based on cis-hydrindane and cis-decalin frameworks has been conceptualized. These novel entities can be regarded as conduritol and carbasugar hybrids. Syntheses of these polyhydroxylated entities have been achieved in stereo- and regioselective manners, starting from the readily available Diels-Alder adducts of 5,5-dimethoxy-1,2,3,4-tetrachlorocyclopentadiene and appropriate dienophiles like cyclopentadiene or p-benzoquinone, that embody a masked 7-ketonorbornenone moiety. Thermally induced chelotropic elimination of CO from the appropriately functionalized 7-ketonorbornenone derivatives to deliver annulated bicyclic 1,3-cyclohexadiene derivatives was the key step in this synthetic endeavor. Further oxy-functionalization of the 1,3-cyclohexadiene moiety delivered the targeted polycyclitols. A preliminary investigation of the glycosidase inhibitory potency of these bicyclitols, identified compounds 18 and 54 as potent and selective inhibitors of alpha-glucosidase (yeast).