Cross-Coupling Reactions of Polyhalogenated Heterocycles

Abstract

AbstractPalladium-catalyzed cross-coupling reactions of polyhalogenated heterocycles provide a convenient access to multifold arylated and alkynylated ring systems with a broad spectrum of physical and medicinal properties. Products include thiophenes, selenophenes, pyrroles, indoles, furans, benzofurans, pyrazoles, pyridines, quinolines, pyrimidines, pyrazines, naphthyridines, quinoxalines, and others. The regioselectivity of the coupling reactions is controlled by a combination of electronic and steric parameters. While a number of couplings can be carried out essentially under standard conditions, others require the use of more sophisticated ligands and a thorough optimization of the conditions, such as solvent, temperature, or reaction time. The present Account provides a personalized overview of coupling reactions of polyhalogenated heterocycles.1 Introduction2 Thiophenes3 Selenophenes4 Pyrroles and Indoles5 Furans and Benzofurans6 Pyrazoles7 Pyridines8 Quinolines9 Pyrimidines and Pyrazines10 Naphthyridines and Quinoxalines11 Miscellaneous12 Conclusions