Pd(II)-Catalyzed ortho- Acylation of Aryl C–H Bond Using─SCN as a Weak Directing Group

Thiocyanate molecules are found in many bioactive natural products including functional materials. Herein, a novel strategy of Pd(II)-catalyzed thiocyanate (-SCN) directed decarboxylative ortho-acylations of benzyl thiocyanates with α-oxocarboxylic acids has been established via ortho-C-H bond activation. Thiocyanate (-SCN) has been probed first time as a directing group in transition-metal-catalyzed C-H bond functionalization. Owing to the simple reaction conditions, this protocol exhibits high regioselectivity with a broad and versatile substrate scope including heterocycles, and secondary thiocyanates to afford excellent yields of products. Density functional theory (DFT) calculations established that the reaction proceeds via sequential coordination of nitrogen as well as sulfur atom of the -SCN group to palladium, involving an unusual monomeric Pd(III) intermediate in the acylation process.