Chemoenzymatic synthesis of isogalactofagomine

A new chemoenzymatic synthesis of optically pure isogalactofagomine 2 start ing from achiral starting materials is presented. Dimethyl 4-hydroxypyridin e-3,5-dicarboxylate (7) was synthesized and converted to the corresponding saturated piperidine 8. Then the key step of the synthesis was carried out: Lipase M catalyzed hydrolysis of the prochiral diester 8 to cause formatio n of an asymmetric monoacid with at least 98% enantiomeric excess. Reductio n of the acid, saponification of the remaining ester, and radical iododecar boxylation gave an iodide that after substitution with silver trifluoroacet ate and hydrolysis gave 2.