Ruthenium-Catalyzed Addition of Primary Amides to Alkynes: A Stereoselective Synthesis of Secondary Enamides

The anti-Markovnikov addition of primary amides to terminal alkynes under the formation of 7 configured secondary enamides is efficiently promoted by a catalyst system generated in situ from bis(2-methallyl)(cycloocta-1,5-diene)ruthenium(II), 1,4-bis(dicyclohexylphosphino)butane, and ytterbium triflate. The thermodynamically more stable E-isomers are accessible by combining the above hydroamidation with an in situ double-bond isomerization reaction, using triethylamine and molecular sieves.