Pd-catalyzed Auto-Tandem Cascades Based on N-Sulfonylhydrazones: Hetero- and Carbocyclization Processes

The Pd-catalyzed cross-coupling between N-tosylhydrazones and organic halides is a powerful method for the creation of C–C bonds. This transformation has been included recently in cascade processes in which the same catalyst promotes various independent catalytic steps, a process known as auto-tandem catalysis. This strategy proves to be very useful for the construction of relatively complex carbo- and heterocyclic structures, as well as for the generation of molecular diversity. This short review will cover the different Pd-catalyzed auto-tandem reactions­ involving N-tosylhydrazones organized by the bond-forming sequence: C–C/C–N and C–C/C–C. Some examples of related tandem reactions leading to acyclic compounds are also highlighted. 1 Introduction 2 Auto-Tandem C–C/C–N Bond-Forming Reactions 3 Auto-Tandem C–C/C–C Bond-Forming Reactions 4 Tandem Reactions for the Synthesis of Linear Molecules 5 Summary and Outlook