A BF3-etherate-promoted cascade reaction of nitriles with 2-alkynylanilines is described. This method achieves the formation of two new C-N bonds through a reaction sequence of diazotization with t-BuONO, nucleophilic addition of the alkyne to the BF3-coordinated diazonium ion, followed by nitrile addition to the intermediary vinyl cation and hydrolysis. The method provides efficient and general access to a variety of 4-amido-cinnolines. Notable features of the method include its broad functional group tolerance and avoidance of transition metals.