In an alternative procedure, nucleophilic displacement of the nitro group from 3-nitro-2-isoxazoline (VI) with lithium benzylate gave the benzyl ether (VII), which was converted to isoxazolidinone (VIII) by catalytic hydrogenation. Alkylation of (VIII) with 1,4-dichloro-2-butyne (IX) resulted in a 4:1 mixture of regioisomers (X) and (XI). After chromatographic isolation, the desired isomer (X) was condensed with pyrrolidine (V) to provide the title compound.

In an alternative procedure, nucleophilic displacement of the nitro group from 3-nitro-2-isoxazoline (VI) with lithium benzylate gave the benzyl ether (VII), which was converted to isoxazolidinone (VIII) by catalytic hydrogenation. Alkylation of (VIII) with 1,4-dichloro-2-butyne (IX) resulted in a 4:1 mixture of regioisomers (X) and (XI). After chromatographic isolation, the desired isomer (X) was condensed with pyrrolidine (V) to provide the title compound.

Alkylation of hydroxylamine with propargyl bromide (I) provided N-propargyl hydroxylamine (II), which was subsequently acylated with 3-chloropropionyl chloride (III) in the presence of pyridine to yield the N-hydroxy amide (IV). Mannich reaction of the propargyl compound (IV) with paraformaldehyde and pyrrolidine (V) with simultaneous cyclization of the N-hydroxy chloropropionamide furnished the title compound.