Scaled-Up Transition-Metal-Catalyzed Cross-Coupling Reactions of Thioether-Substituted N-Heterocycles with Organozinc Reagents

摘要

A variety of functionalized methylthio-substituted N-heterocycles (pyridines, pyrimidines, pyrazines, pyridazines, triazines, quinazolines, benzothiazoles) undergo smooth palladium- or nickel-catalyzed cross-couplings with highly functionalized organozinc reagents at ambient temperature. No expensive copper(I) salts are required and the coupling reactions proceed readily in the range of up to 20 mmol scale. Transition-metal-catalyzed cross-coupling reactions between unsaturated halides and organometallics of Zn, Mg, and B are important tools in organic chemistry for the formation of carbon-carbon bonds. A major drawback is that halogen-substituted heterocycles, which are used as electrophiles in such cross-coupling reactions, are sometimes difficult to prepare and may be unstable.