Fipronil-based photoaffinity probe for Drosophila and human β3 GABA receptors

Modification of the major insecticide fipronil (1) by replacing three pyrazole substituents (hydrogen for both cyano and amino and trifluoromethyldiazirinyl for trifluoromethylsulfinyl) gives a candidate photoaffinity probe (3) of high potency (IC50 2–28 nM) in blocking the chloride channel of Drosophila and human β3 GABA receptors.