Recent Developments in Palladium-Catalyzed Formation of Five-and Six-Membered Fused Heterocycles

Palladium-mediated cyclization reactions have been recognized as some of the simplest and useful tools for regio- as well as stereoselective syntheses of carbo-and heterocyclic compounds. In the multi-step syntheses of natural products it is frequently used as one of the most important steps. In this review article, we have summarized the various ways of constructing five-and six-membered heterocyclic rings by palladium-catalyzed intramolecular cyclizations published between 2008 and 2010. 1 Introduction 2 Synthesis of Heterocycles via Alkene Cyclizations 2.1 Intramolecular Heck Cyclizations of Vinylic Halides 2.2 Intramolecular Heck Cyclizations of Aryl Halides 2.3 Intramolecular Heck Reactions of Aryl Triflates 2.4 Intramolecular Hydroxylations of Alkenes 2.5 Intramolecular Aminations of Alkenes 2.6 Intramolecular Annulations of Alkenes via Double C-H Activations 2.7 Intermolecular Annulations of Alkenes 3 Synthesis of Heterocycles via Alkyne Cyclizations 3.1 Intramolecular Cyclizations of Internal Alkynes 3.2 Intramolecular Cyclizations of Terminal Alkynes 3.3 Intermolecular Annulations of Alkynes 4 Synthesis of Heterocycles via Allene Cyclizations 5 Intramolecular Biaryl-Coupling Reactions 6.1 Biaryl Couplings via C-X Functionalizations 6.2 Biaryl Couplings via Double C-H Activations 6 Heterocycles via Carbonylative Cyclizations 7 Synthesis of Heterocycles from Alkane Substrates 8 Miscellaneous 9 Conclusion