TCCA/PhSH-mediated regioselective hydroethoxylation and hydromethoxylation of allenamides via a radical process

An efficient TCCA/PhSH-mediated regioselective hydroethoxylation and hydromethoxylation of allenamides via a radical process was developed to create a workable route to γ-oxygenated enamides. This process is highly regioselective, affording (E)-γ-oxygenated enamides in moderate to good yields. Mechanistic investigations indicated that the ethoxy radical was formed through the activation of TCCA/PhSH, which subsequently added to the terminal carbon of allenamides to form a vinyl radical intermediate. The efficiency of the gram-scale reaction suggests the potential industrial application of this synthetic method. Notably, our approach eliminates the need for metal catalysts, representing a significant advancement in green chemistry practices.