合成路线1

Reaction of 4-cyanobenzaldehyde (I) with hydroxylamine sulfate in methanol gives 4-cyanobenzaldoxime (II). A 1,3-dipolar cycloaddition of (II) with isobutyl vinylacetate using N-chlorosuccinimide provides the racemic isoxazoline derivative (III). Treatment of (III) with lipase PS30 selectively converts the (R)-isomer to an optically pure acid (IV). Coupling of (IV) with methyl N2-(n-butyloxycarbonyl)-L-2,3-diaminopropionate (VI), which is derived from its corresponding commerically available acid (V), gives the intermediate (VII). Treatment of (VII) with HCl in methanol and ethyl acetate followed by ammonium acetate affords DMP 754 as a crystalline product. Saponification of DMP 754 using LiOH provides the corresponding acid (VIII).