A series of sp2-iminosugar glycomimetics differing in the reducing or nonreducing character, the configurational pattern (d-gluco or l-ido), the architecture of the glycone skeleton, and the nature of the nonglycone substituent has been synthesized and assayed for their inhibition properties towards commercial glycosidases. On the basis of their affinity and selectivity towards GH1 β-glucosidases, reducing and nonreducing bicyclic derivatives having a hydroxylation profile of structural complementarity with d-glucose and incorporating an N′-octyl-isourea or -isothiourea segment were selected for further evaluation of their inhibitory/chaperoning potential against human glucocerebrosidase (GCase). The 1-deoxynojirimycin (DNJ)-related nonreducing conjugates behaved as stronger GCase inhibitors than the reducing counterparts and exhibited potent chaperoning capabilities in Gaucher fibroblasts hosting the neuronopathic G188S/G183W mutation, the isothiourea derivative being indeed one of the most efficient chaperone candidates reported up to date (70% activity enhancement at 20 pM). At their optimal concentration, the four selected compounds promoted mutant GCase activity enhancements over 3-fold; yet, the inhibitor/chaperoning balance became unfavorable at much lower concentration for nonreducing as compared to reducing derivatives.

A series of bicyclic isourea derivatives were prepared from 1-deoxynojirimycin using a concise synthetic protocol proceeding via a guanidino intermediate. Inhibition assays with a panel of glycosidases revealed that these deoxynojirimycin-derived bicyclic isoureas display very potent inhibition against human recombinant β-glucocerebrosidase with IC50 values in the low nanomolar range.

A series of lipidated guanidino and urea derivatives of 1,5-dideoxy-1,5-imino-d-xylitol were prepared from d-xylose using a concise synthetic protocol. Inhibition assays with a panel of glycosidases revealed that the guanidino analogues display potent inhibition against human recombinant β-glucocerebrosidase with IC values in the low nanomolar range. Related urea analogues of 1,5-dideoxy-1,5-imino-d-xylitol were also synthesized and evaluated in the same fashion and found to be selective for β-galactosidase from bovine liver. No inhibition of human recombinant β-glucocerebrosidase was observed for the urea analogues. Computational studies provided insight into the potent activity of analogues bearing the substituted guanidine moiety in the inhibition of lysosomal glucocerebrosidase (GBA).

Two novel 4-substituted camphidine derivatives 10a,b have been prepared from (+)-camphor (1) in five steps, the Beckmann rearrangement being the bottleneck of the synthesis. Isoborneol derivative 5b, formed as a side product during the hydrogenation of arylidene ketone 3b, under Beckmann rearrangement conditions yielded interesting novel rearrangement products 11 and 12. (1S)-(+)-Camphorquinone (13) was transformed into diamines 15 and 16 in two steps, the former being cyclized into an imidazoline salt 17, an N-heterocyclic carbene precursor. The structures of all novel compounds have been meticulously characterized using NMR techniques and/or single crystal X-ray analysis.