2-Mercapto-4-quinazolone (I) is treated with ethyl iodide (II) in the presence of sodium ethoxide to yield 2-ethylthio-4-quinazolone (III). Reaction of (III) with N-benzylpiperazine (IV) to give (V) and followed by catalytic debenzylation with H2 over Pd/C in glacial acetic acid affords Centpiperalone.

The ethanolysis of 1-benzylpyrrolidin-2-one (I) with HCl in ethanol gives 4-(benzylamino)butyric acid ethyl ester (II), which is alkylated with ethyl bromoacetate (III), yielding the tertiary amine (IV). The cyclization of (IV) by means of sodium ethoxide affords 1-benzyl-3-hydroxy-1,2,5,6-tetrahydropyridine-4-carboxylic acid ethyl ester (V), which by hydrogenolytic debenzylation, followed by reaction with methyl chloroformate (VI), affords the 1,4-dicarboxylate (VII). The reaction of (VII) with ethyleneglycol (VIII) and TsOH gives the cyclic ketal (IX), which is treated with hydroxylamine and NaOMe to yield the carbohydroxamic acid (X). The cyclization of (X) by means of H2SO4 affords 3-hydroxy-4,5,6,7-tetrahydropyrido[4,3-d]oxazole-6-carboxylic acid methyl ester (XI), which is finally decarboxylated by means of HBr and TEA.

2-Mercapto-4-quinazolone (I) is treated with ethyl iodide (II) in the presence of sodium ethoxide to yield 2-ethylthio-4-quinazolone (III). Reaction of (III) with N-benzylpiperazine (IV) to give (V) and followed by catalytic debenzylation with H2 over Pd/C in glacial acetic acid affords Centpiperalone.

2-Mercapto-4-quinazolone (I) is treated with ethyl iodide (II) in the presence of sodium ethoxide to yield 2-ethylthio-4-quinazolone (III). Reaction of (III) with N-benzylpiperazine (IV) to give (V) and followed by catalytic debenzylation with H2 over Pd/C in glacial acetic acid affords Centpiperalone.