Sequential regioselective arylation of pyrazolones with diaryliodonium salts

The introduction of aromatic substituents into organic compounds significantly alters their physical and chemical characteristics. Yet, achieving precise control over the site-selectivity of arylation continues to pose a considerable challenge. We present here a controllable method for the site-selective mono-, di-, and triarylation of pyrazolone with diaryliodonium salts. The method showcases robustness, flexibility, and excellent compatibility with a broad range of functional groups. It enables control over both the site of arylation and the number of aryl additions. Specifically, three of the four substitutable positions in pyrazolone can be selectively arylated, effectively producing four products under controlled conditions. Additionally, the method supports one-pot sequential arylation, leading to an array of products with diverse aromatic substituents. Control experiments revealed the specific conditions of each reaction step.