Cyclometalated (NNC)Ru(ii) complex catalyzed β-methylation of alcohols using methanol

Abstract

Indolyl fragment containing phenanthroline based new ligands and their corresponding Ru(II) complexes were synthesized and fully characterized by various spectroscopic techniques. The catalytic activity of these newly synthesized cyclometalated (NNC)Ru(II) complexes was explored towards the β-methylation of alcohols using methanol. Notably, these complexes displayed superior reactivity compared to various (NNN)Ru(II) complexes. Utilizing this strategy, a wide range of primary, secondary, and aliphatic straight chain alcohols were selectively methylated. This protocol was further employed for the methylation of a few natural products and the gram scale synthesis of β-methylated alcohols. A series of control experiments and kinetic studies were performed to understand the plausible reaction mechanism.