Pd-catalyzed site selective C-H acetoxylation of aryl/heteroaryl/thiophenyl tethered dihydroquinolinones

Described herein is an efficient protocol for the site selective oxidative C-H activation/acetoxylation of a series of 2-aryl/heteroaryl/thiophenyl tethered dihydroquinolinones using palladium acetate as the catalyst and iodobenzene diacetate as an oxidant. All these transformations progressed well at less sterically encumbered and electronically favourable C-H bonds to give corresponding ortho-acetoxylated derivatives in good yields. Further, acetoxylation of thiophenyl embedded dihydroquinolinones resulted in single regioisomers, acetoxylated at the C-2 position on the thiophenyl moiety. However, when the C-2 position on the thiophene unit was blocked, the acetoxy group was exclusively installed at the C-4 position. Further, we noticed that acetoxylation of dihydroquinolin-5(6H)-one-oxime did not alter ligand preferentiality to give the ortho-acetoxylated product.