Ruthenium-catalyzed C-H functionalization of arylpyrazoles: regioselective acylation with acid chlorides.

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.