Synthesis of 4-alkyl-3,5-diamino-1-phenylpyrazoles

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Dunham, Jason C.
Sammelson, Robert E.
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Thesis (M.S.)
Department of Chemistry
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The goal of this project is to synthesize and purify a library of novel 4-alkyl-3,5-diamino-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazoles. These molecules are similar to other fiproles, which have been shown by Sammelson et al. to have pesticidal activities at the GABA receptor.' Fiproles are analogues of Fipronil, a very important pesticide. Replacing the cyano group normally located at the 3-position of the pyrazole ring with an amino group will change the binding potency of the phenylpyrazoles. Changes in binding produced by the changes introduced in molecular structure can create more information about the GABA receptor.Synthesis of our target compounds starts with production of monosubstituted malononitriles. Conventionally a two-step process, our research developed a new, efficient one-step process using borohydride as the only reagent. We utilized this method in the synthesis of desired monosubstituted malononitriles. These were converted to unsymmetrical disubstituted malononitriles, and to our target fiprole compounds, through a 4-alkyl-3,5-diaminopyrazole intermediate.