Condensation between 3-amino-2-chloropyridine (I) and 3,4-diethoxycyclobut-3-ene-1,2-dione (II) in refluxing EtOH affords the (pyridylamino)cyclobutenedione (III). The remaining ethoxy group of (III) is then displaced with methanolic ammonia to furnish the diamino cyclobutenedione (IV).

Reaction of 3,5-dichlorobenzamide (V) with pivalaldehyde (VI) in the presence of benzotriazole (VII) gives rise to the benzotriazolyl benzamide (VIII). This is then condensed with the diamino cyclobutene (IV) to afford the racemic adduct (IX), which is finally resolved into the enantiomers employing chiral chromatography.

Reaction of 3,5-dichlorobenzamide (V) with pivalaldehyde (VI) in the presence of benzotriazole (VII) gives rise to the benzotriazolyl benzamide (VIII). This is then condensed with the diamino cyclobutene (IV) to afford the racemic adduct (IX), which is finally resolved into the enantiomers employing chiral chromatography.