Selective sulfonylation of 4-C-hydroxymethyl-β-l-threo-pento-1,4-furanose: synthesis of bicyclic diazasugars

Abstract

Hydroxymethylation of α-D-xylo-pentodialdose 6 using excess formaldehyde and sodium hydroxide in THF-water (one pot aldol and crossed Cannizzaro reactions) followed by hydrogenolysis of C3-O-benzyl group afforded triol 8. The regio-selective α- and β-sulfonylation of hydroxymethyl groups in 8 afforded 9a (α-sulfonylation) and 14 (β-sulfonylation) in good yield. The cleavage of the 1,2-acetonide functionality, individually in 9a and 14, followed by reaction with 1,3-diaminopropane gave in situ formation of sugar aminals, that undergo concomitant nucleophilic displacement of the sulfonyloxy group by amino functionality to give hitherto unknown bicyclic diazasugars 4 and 5, respectively, with a hydroxymethyl substituent at C-7.