Three-Component Friedel–Crafts Alkenylation of Arenes and Heteroarenes with Ynamides and Iodine(III) Electrophile

The three-component Friedel–Crafts type functionalization of an arene using an alkyne and an electrophile can offer a strategy for rapidly increasing the molecular complexity of aromatic compounds. While conceptually straightforward, the implementation of this reaction manifold has been largely limited to unfunctionalized alkynes and electrophiles such as iodine(I) reagents. Here, we report the development of a three-component Friedel–Crafts alkenylation that utilizes a mix of ynamides and a cationic iodine(III) electrophile (benziodoxole triflate). The reaction proceeds quickly under mild conditions across diverse arenes and heteroarenes, producing α-aryl-β-iodanyl enamides in a regio- and stereocontrolled manner. The robust trans-selectivity of this iodo(III)arylation process is attributed to the reactivity of a highly distorted keteniminium species generated from the ynamide and the iodine(III) electrophile. The iodanyl moiety in these reaction products is amenable to a variety of transition metal-mediated coupling, thus offering access to densely functionalized enamides.