N-Aryl-2-cyanodiazoacetamidesp roduce polycyclic difluoroboron 2-oxoindoline-3-carboxamide complexes (up to pentacyclic conjugative and fused systems) directly ande xpeditiously in the presence of boron trifluoride etherate.T he boront rifluoride serves as both ac atalyst and reactant in the tandem reaction. Thet andem reactioni ncludes the carbenea romatic C À Hi nsertion, hydrolysiso ft he cyano group into an amide group,a nd boronation of the two amide carbonyl groups.T he synthetic method features the advantages of wide substrate scope and excellent chemoselectivity. Scheme3.Rationalef or the BF 3 -catalyzed hydrolysis of 2cyano-N,N-diphenylacetamide (4a).Scheme 4. Proposed mechanism for the tandemr eaction. 1 HNMR (400 MHz, CDCl 3 ): d = 7.26-7.04 (m, 4H), 3.82 (s, 2H), 3.65 (s,2H), 2.74 (s,2H), 2.04-1.96 (m, 2H); 13 CNMR