Z-Selective hydroamidation of terminal alkynes with secondary amides and imides catalyzed by a Ru/Yb-system

A catalyst system formed in situ from bis(2-methallyl)cycloocta-1,5-diene-ruthenium(II) [(cod)Ru(met)2], 1,4-bis(dicyclohexylphosphino)butane (dcypb) and ytterbium(III) triflate hydrate (Yb(OTf)3) was found to catalyze the addition of nitrogen nucleophiles to terminal alkynes under mild conditions to stereoselectively form the Z-enamide or Z-enimide products. Various secondary amides and imides could be added across the triple bond of a range of aliphatic and aromatic alkynes. The new bimetallic catalyst system sets new standards with regard to scope and selectivity for the synthesis of Z-configured anti-Markovnikov enamides.

A Ru-phosphine catalyst in combination with the Lewis acid Yb(OTf)3 has been found to promote the regio- and stereoselective addition of secondary amides and imides under selective formation of the Z-configured anti-Markovnikov products. The new protocol provides an atom-economic entry to the thermodynamically disfavored Z-isomers of various synthetically important enamides and enimides.Figure optionsDownload as PowerPoint slide