A general synthesis for ethyl 3, 3-dialkyl-and 3-aryl-1, 2, 2- tricyanocyclopropanecarboxylates from bromomalononitrile and ylidenecyanoacetates is described. When stereoisomeric products are possible, the predominant and sometimes exclusive isomer obtained has the larger C-3 substituent and the ethoxycarbonyl group in the trans-position.
