Nitroacetaldehyde oxime (I) is formed from nitromethane in the presence of NaOH and is converted in acidic media with 2-aminobenzoic acid (II) to 2-(2-nitroethylideneamino)benzoic acid (III). Cyclization of (III) in acetic anhydride by means of potassium acetate yields 4-hydroxy-3-nitroquinoline (IV), which is converted to 4-chloro-3-nitroquinoline (V) in boiling POCl3. Reaction of (V) with morpholinecarboximidamide (VIII) (formed from morpholine (VI) and S-methylisothiourea hemisulfate (VII) in ethanol) affords troquidazole.