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Paper | Regular issue | Vol 63, No. 6, 2004, pp.1311-1334
Published online, 9th April, 2004
DOI: 10.3987/COM-04-10046
Synthesis and NMR Spectroscopic Investigations with 3-Amino-, 3-Hydroxy-, and 3-Methoxy-4-acyl-1-phenyl-2-pyrazolin-5-ones

Wolfgang Holzer* and Linda Hallak

*Institute of Pharmaceutical Chemistry, University of Vienna, Pharmaziezentrum, Althanstraße 14, A-1090 Vienna, Austria


Reaction of 3-amino-, 3-hydroxy- and 3-methoxy-1-phenyl-2-pyrazolin-5-one with carboxylic acid chlorides / calcium hydroxide in 1,4-dioxane mainly affords the corresponding 4-acyl-2-pyrazolin-5-ones. 3-Methoxy-1-phenyl-2-pyrazolin-5-one reacts with dimethylformamide diethyl acetal to give an (E)/(Z)-mixture of the 4-dimethylaminomethylene product, with tetracyanoethylene the 4-dicyanomethylene product is obtained, whereas with nitrous acid the 4-hydroximino derivative results. NMR-spectroscopic investigations (1H, 13C, 15N) with the obtained reaction products are presented.