Regioselective Direct C–H Bond Heteroarylation of Thiazoles Enabled by an Iminopyridine-Based α‑Diimine Nickel(II) Complex Evaluated by DFT Studies

Direct
C–H bond arylation is a highly effective method for
synthesizing arylated heteroaromatics. This method reduces the number
of synthetic steps and minimizes the formation of impurities. We report
an air- and moisture-stable iminopyridine-based α-diimine nickel(II)
complex for direct C5–H bond arylation of thiazole derivatives.
Under a low catalyst loading and performing the reactions at lower
temperatures (80 °C) under aerobic conditions, we produced mono-
and diarylated thiazole units. Competition experiments and density
functional theory calculations revealed that the mechanism of C–H
activation in 4-methylthiazole involves an electrophilic aromatic
substitution.