Precise manipulation of electron transfers to enable the site-selective hydropyridylation of ynones

Abstract

Precise manipulation of electron transfers for site-selective hydropyridylation of ynones for the synthesis of β-pyridyl ketones and pyridinated propargyl alcohols tends to be an attractive strategy but remains a challenging task. Herein, the site-tunable hydropyridylation of ynones was successfully delivered by precisely manipulating the electron transfer under electrochemical conditions using square wave voltammetry as a powerful tool. Mechanistic investigations revealed that solvation and suitable protonation reagents are crucial factors in controlling the electron transfer order of ynones to modulate active free radical sites. In addition, the kinetic studies demonstrate that the hydrogenation of ynones on the surface of the cathode should be the rate determining step.