Pd/Cu cooperative catalysis: an efficient synthesis of (3-isoindazolyl)allenes via cross-coupling of 2-alkynyl azobenzenes and terminal alkynesElectronic supplementary information (ESI) available. CCDC 1522907 and 1522908. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7cc00562h

An efficient synthesis of (3-isoindazolyl)allenes from 2-alkynyl azobenzenes and terminal alkynes via cooperative Pd(PPh 3 ) 2 Cl 2 /CuI-catalyzed cross-coupling has been developed. By making use of this approach, (3-isoindazolyl)allenes with various substituents can be synthesized in good to excellent yields. A rapid synthesis of biologically active indazolo[2,3- a ]quinoline was also achieved using this method as the key step. We report a cooperative Pd/Cu-catalyzed synthesis of (3-isoindazolyl)allenes via cross-coupling of 2-alkynyl azobenzenes and terminal alkynes.