合成路线1

The selective reduction of methyl nicotinate (I) with simultaneous protection of the resulting NH group with phenyl chloroformate gives the 1,2-dihydropyridine derivative (II), which is treated with MCPBA (III) to afford the hydroxyester (IV). The reduction of (IV) with Tms-OTf and borane/THF complex affords the allylic alcohol (V), which is oxidized with CrO3 in acetone to provide the ketone (VI). The asymmetric reduction of (VI) with LiAlH4 catalyzed by (-)-N-methyl-ephedrine gives the chiral alcohol (VII), which is treated with refluxing 1N HCl to yield the carboxylic acid (VIII).The reduction of (VIII) with borane/THF complex and H2O2 affords the chiral carbinol (IX), which is finally deprotected by treatment with LiOH to provide the target isofagomine.