Regio- and Stereoselective Hydrophosphorylation of Ynamides: A Facile Approach to (Z)-beta-Phosphor-Enamides

The first trans-selective beta-hydrophosphorylation of ynamides, which provides a facile approach to (Z)-beta-phosphor-enamide derivatives in moderate to excellent yields and with excellent regio- and stereoselectivity, is described. This transition-metal-free reaction is featured with operationally simple procedure, mild reaction conditions, readily available starting materials, broad substrate scope and good functional-group tolerance. It is noted that the (Z)-beta-phosphor (V)-enamides can be prepared from the oxidation of the corresponding phosphine derivatives or the direct beta-hydrophosphorylation of ynamides with diphenylphosphine oxide. In addition, cis-trans isomerization of (Z)-beta-phosphor (V)-enamides can be easily realized to furnish the corresponding (E)-beta-phosphor (V)-enamides. This advantageous feature enables the preparation of (Z)-beta-phosphor (V)-enamides as well as (E)-beta-phosphor (V)-enamides from the same starting materials.