Pd(II)-catalyzed monoarylation of 2-phenylpyridine N-oxide with iodobenzene in water

A Pd(II)-catalyzed activation and arylation of C(sp2)–H bond directed by pyridine N-oxide in water is achieved with high regioselectivity to form monoarylated products in yields up to 91%. The wide substrate scope highlights the flexibility of the catalyst. The reaction mechanism was proposed and the application of this method was taken as an example by the synthesis of COX-2 inhibitor analog.