A Density Functional Theory Study of Ru‐Catalyzed Self‐Coupling Reaction of Secondary Alcohols

ABSTRACT The ruthenium complex catalyzed self‐coupling reaction of secondary alcohols is an environmentally friendly strategy for the synthesis of β‐branched ketones. In order to understand the reaction mechanism, a density functional theory (DFT) study was carried out using 1‐phenylethanol as substrate. The catalytic cycle is mainly composed of three stages. The first stage is the dehydrogenation of 1‐phenylethanol and hydrogen generation, the second stage is the self‐coupling of aldehydes, and the third stage is hydrogenation of α,β‐unsaturated ketone. DFT calculations indicate that 1‐phenylethanol‐assisted dehydrogenation is superior to direct dehydrogenation. The hydrogenation of α,β‐unsaturated ketone via 1, 4‐addition is more favorable than that via 1,2‐addition, and the corresponding product is more stable. The mechanistic insights gained in this study would be helpful in improving the current reaction system or designing new catalysts.