A ruthenium-catalyzed C-H acylation of arylpyrazoles with a variety of acyl chlorides is described. The acylation reaction exhibits good regioselectivity and both aromatic and aliphatic acyl chlorides can be effectively coupled to the arylpyrazoles at the ortho-position.
Liu, P. M., & Frost, C. G. (2013). Ruthenium-catalyzed C-H functionalization of arylpyrazoles: Regioselective acylation with acid chlorides. Organic Letters, 15(22), 5862-5865. https://doi.org/10.1021/ol402936c