Reaction sequences in organic syntheses either require protection groups or careful planning of the reaction pathway when dealing with(or avoiding)ambident molecules,due to numerous byproducts.A protocol in a micro reactor was developed to determine the dominant mechanics behind a fast reaction on a bifunctional molecule.Using this protocol,terephthaldialdehyde was successfully converted in a Wittig reaction to the respective stilbene compound,while leaving the second aldehyde functionality untouched.