Catalytic intermolecular hydrofunctionalizations of ynamides

Ynamides are electron-rich alkynes with a carbon–carbon triple bond directly attached to the nitrogen atom bearing an electron-withdrawing group. This unique structure renders diverse reactivities to ynamides in synthetic chemistry. Among them, the catalytic intermolecular hydrofunctionalization of ynamides is of critical importance, which enables a rapid and atom-economical synthesis of multi-substituted enamides with high and tunable chemo-, regio-, and stereoselectivity. This review provides a comprehensive summary of the hydrofunctionalization of ynamides and is categorized by the bond formation types including C–C, C–X, C–O, C–N, C–S, C–P, C–Si, and C–Ge bonds. Based on their position in making new bonds, the reactions can be classified into four types: the syn-α-adduct, syn-β-adduct, anti-α-adduct and anti-β-adduct. This review will facilitate a better understanding of the factors that contribute to the varied selectivities and arouse more research interest in this fascinating topic.