Copper-Catalyzed Regio- and Stereoselective Hydrothiolation of Allenamides, Enamides, and Ynamides

Abstract

We report a simple protocol for the copper-catalyzed hydrothiolation of N-unsaturated precursors, i.e., allenamides, enamides, and ynamides, under mild conditions. This method proceeds with a low loading of a commercially available Cu­(CH3CN)4PF6 catalyst and enables the room-temperature transformation of a wide range of aromatic and aliphatic thiols into allylic or vinylic thioethers, 1,3-dithioethers, and thioaminals with good regio- and stereoselectivity.

Selective Hydrofunctionalization of N-Allenyl Derivatives with Heteronucleophiles Catalyzed by Brønsted Acids

“…We were pleased to observe good results with primary, secondary, and tertiary aliphatic thiols ( 8ba - 8bd ) as well as with toluenesulfinic acid ( 8bf ), all yielding the corresponding γ-sulfur-substituted enamides at room temperature. These results are particularly noteworthy, since the addition of thiols to allenamides is rarely described in the literature and the reported methods lead to structurally different products or require metal-catalysis or stoichiometric TFA addition . It is interesting to note that thiophenol acts as a thio-nucleophile, selectively yielding the corresponding γ-sulfur enamide 8be , contrary to phenol, which takes part in a Friedel–Crafts-type reaction (Scheme ).…”

Catalytic intermolecular hydrofunctionalizations of ynamides

“…Recently, Taillefer and Monnier et al exploited an efficient syn -β-hydrothiolation of internal ynamides with thiols enabled by copper catalysis (Scheme 56). 105 The aryl substituents on the ynamide terminus were well compatible with the transformation, exclusively providing ( E )-β-thiylenamides in moderate to good yields. In comparison, subjecting alkyl-substituted ynamides to the standard conditions afforded unexpected α-thiylenamides with a moderate ratio of E - and Z -configuration.…”