合成路线1

Michael addition of 1-nitrohexane (I) to methyl crotonate (II) provided nitroester (III) as a mixture of diastereoisomers. Reduction and cyclization of (III) by hydrogenation over Raney Nickel gave the cis- (IV) and trans- (V) pyrrolidinones, which were separated by column chromatography. Racemic cis isomer (IV) was resolved upon condensation with (R)-(+)-1-naphythylethyl isocyanate (VI) in boiling benzene, followed by chromatographic separation of the resulting diastereomeric mixture of ureides. The desired isomer (VII) was then hydrolyzed with sodium butoxide in refluxing n-BuOH to furnish the (+)-cis pyrrolidinone (+)(IV). Subsequent treatment with trimethyloxonium tetrafluoborate produced the iminoether (VIII), which was finally reacted with NH4Cl in refluxing MeOH to provide the corresponding iminopyrrolidine.