合成路线1

The reaction of N,N-dibenzyl-L-alaninal (I) with nitromethane, catalyzed by the chiral ammonium salt (II) and KF in THF gives the chiral nitroalcohol (III), which is reduced with NiCl2 and NaBH4 to yield the aminoalcohol (IV). The condensation of (IV) with isobutyraldehyde (V) affords the Schiff base (VI), which is reduced with NaBH4 to provide the secondary amine (VII). The reaction of (VII) with 4-nitrobenzenesulfonyl chloride (VIII) and TEA in dichloromethane furnishes the sulfonamide (IX), which is deprotected by hydrogenation with H2 over Pd/C in methanol, giving the diamino compound (X). Finally, this compound is condensed with 3(S)-tetrahydrofuryl (N-oxysuccinimidyl) carbonate (XI) by means of TEA in dichloromethane to afford the target carbamate.