Regioselective ortho-hydroxylation of 2-arylbenzothiazole via substrate directed C–H activation

An efficient protocol has been developed for the direct ortho-hydroxylation of 2-arylbenzothiazole using Pd(OAc)2 as the catalyst and either of DIB/AcOH or Oxone®/TFA combinations under air atmosphere. Under both these conditions, the methodology tolerates a diverse array of substituents giving good to excellent yields of corresponding ortho-hydroxylated products. Regioselective hydroxylation is observed at the less sterically hindered site of the phenyl ring possessing substituents at its meta position.