Cross‐Coupling Reactions of Organotrifluoroborate Salts

Organotrifluoroborates are partners for cross-coupling that have emerged as complementary and often unique alternatives to other organoboron reagents. This chapter provides a comprehensive overview of all cross-coupling reactions of the various classes of organotrifluoroborates that have been carried out through August, 2009. The chapter introduces the subject with a discussion of mechanistic considerations concerning the cross-coupling, followed by a brief discussion of the stereochemical aspects of the transformation. The scope and limitations of the reactions are subsequently discussed, first in terms of the organotrifluoroborate and then the electrophilic partner of the reaction. Potential side reactions that are encountered are outlined with useful suggestions on how these can be avoided in practice. Applications in synthesis are described, detailing how organotrifluoroborates have been utilized in the construction of natural products, materials of all types, and pharmacologically active substances. A comparison to other cross-coupling methods rounds out the descriptive part of the chapter. A detailed outline of experimental considerations and protocols has been assembled, gleaning information from the vast array of published procedures to assemble an overview of the most successful conditions. Representative procedures are included for each class of organotrifluoroborate coupling partner, and the tables provide a comprehensive listing of individual reactions. Keywords: organotrifluoroborates; Suzuki-Miyaura cross-coupling; palladium catalysis; nickel catalysis; ligands; biaryl synthesis