Synthesis of N ‐Substituted (3 S ,4 S )‐ and (3 R ,4 R )‐Pyrrolidine‐3,4‐diols: Search for New Glycosidase Inhibitors

N ‐Substituted (3 S ,4 S )‐ and (3 R ,4 R )‐pyrrolidine‐3,4‐diols 9 and 10 , respectively, were derived from (+)‐ L ‐ and (−)‐ D ‐tartaric acid, respectively. Compounds 9k, 9l , and 9m with the N ‐substituents, BnNH(CH 2 ) 2 , 4‐PhC 6 H 4 CH 2 NH(CH 2 ) 2 and 4‐ClC 6 H 4 CH 2 NH(CH 2 ) 2 , respectively, showed modest inhibitory activities toward α ‐ D ‐amyloglucosidases from Aspergillus niger and from Rhizopus mold ( Table 1 ). Unexpectedly, several (3 R ,4 R )‐pyrrolidine‐3,4‐diols 10 showed inhibitory activities toward α ‐ D ‐mannosidases from almonds and from jack bean ( Table 3 ). N ‐Substitution by the NH 2 (CH 2 ) 2 group, i.e. , 10g , led to the highest potency.