Experimental and Computational Studies on Remote γ-C(sp3)-H Silylation and Germanylation of Aliphatic Carboxamides

A Pd(II)-catalyzed protocol for highly regioselective distal gamma-C-H silylation and germanylation of aliphatic carboxylic acids is reported. Bidentate 8-aminoquinoline as the directing group was found to stabilize the six-membered palladacycle. A variety of aliphatic carboxylic acids and amino acids were silylated and germanylated in good yields and high diasteroselectivities. Detailed mechanistic studies involving isolation of a Pd(II) intermediate, determination of the reaction rate and order, control experiments, and isotopic labeling and DFT studies were found to be crucial for elucidating the elementary steps involved in this distal aliphatic functionalization.