Enantiospecific synthesis of 1-azafagomine

Article abstract of DOI:10.1002/(SICI)1521-3765(20000117)6:2<278::AID-CHEM278>3.0.CO;2-6

For the first time the two enantiomeric forms of the glycosidase inhibitor 1-azafagomine have been synthesised starting from D- and L-xylose. D-Xylose was converted to the 2,3,5-tribenzylfuranose, which upon reductive amination with tert-butyl carbazate gave the protected 1-hydrazino-1- deoxypentitol in high yield. N-acetylation, mesylation of the 4-OH, removal of the Boc group, cyclisation and deprotection gave (+)-1-azafagomine ((+)- 1). By a similar sequence of reactions, L-xylose was converted to (-)-1- azafagomine ((-)1). Enzymatic and other routes to optically pure 1- azafagomine were also studied. Compound (-)-1 is a potent competitive glycosidase inhibitor, while (+)-1 has no biological activity. The inhibition of almond β-glucosidase by (-)-1 was found to be slow owing to a slow binding step of inhibitor to enzyme, with no subsequent conformational rearrangement. The rate constants for binding and release were found to be 3.3 x 10⁴ M^-1 s^-1 and 0.011 s^-1, respectively, yielding K(i) = 0.33 μM.