The three-component reaction of sulfonium salts 1, malononitrile 3, and aldehydes 2 in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) or in EtOH in the presence of Et3N is a convenient one-pot method for synthesis of substituted 1,1-dicyanocyclopropanes (7 and 9). The reaction of compounds 1-3 occurs stereoselectively to form substituted trans-cyclopropanes (7), whose structures were confirmed by the data of physicochemical methods, including X-ray diffraction analysis. The yield of cyclopropanes produced by the reaction in the ionic liquid is 8-21% higher than that in EtOH.