An efficient synthesis of 2-(N-aryl)aminobenzo[d]-1,3-thiazoles viaintramolecular C–S bondformation/C–H bondfunctionalization utilizing an unusual cocatalytic Au-NPs/KMnO4 system under an oxygen atmosphere at 80 °C is presented. Au-NPs can be easily prepared by using HAuCl4 with reductive potential of Kayea assamica (sia nahor) aqueous fruit extract. The catalyst can be easily separated and recycled