Ruthenium catalyzed selective oxidation of aryl thiophenes using hydrogen peroxide

Highly selective catalytic oxidations of (sterically hindered) aryl thiophenes using stoichiometric amounts of hydrogen peroxide (35% in water) and cis-Ru(II) bis(substituted phenanthroline) complexes (as low as 0.1%) were carried out in acetonitrile at 75 °C, affording the corresponding sulfones in high yields and selectivities. The products were recovered quantitatively by simple crystallization from the reaction mixture.

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