Abstract 2-Haloethylidenemalonates are highly reactive species and useful synthons for the synthesis of Famvir®, an antiviral drug. Simple methods for the preparation of 2-haloalkylidenemalonates are not available. We have developed a novel and non-cumbersome methodology for the synthesis of dialkyl 2-(2-haloethylidene)malonates, cyanoacetates and halocrotonates by one carbon extension of dialkyl (2-alkoxymethylene)malonates, cyanoacetates and 3-alkoxyacrylates with dimethylsulfoxonium methylide. © 2015 Elsevier Ltd.