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

Abstract

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.