A method for the preparation of 3-fluoroalkyl substituted 2-aza-butadienes by aza-Wittig reaction of N-vinylic phosphazenes and aldehydes is reported. [4+2] Cycloaddition reaction with enamines affords fluoralkyl Substituted pyridine derivatives in a regioselective fashion. (C) 2004 Elsevier Ltd. All rights reserved.