Coinage (Au, Ag, Cu) metal-catalyzed (3 + 2) annulation of α-aminoketones and electron-deficient alkynes as a route to 3-EWG-substituted pyrroles

Coinage (Au, Ag, Cu) metal-catalyzed (3 + 2) annulation of α-aminoketones and electron-deficient alkynes provides a modular one-step route to a variety of 3-EWG-substituted pyrroles. Apart from gold( i ) complexes, which "open any door" and catalyze the annulation regardless of the identity of the alkyne EWGs [-SO 2 R, -CO 2 R, -PO(OR) 2 ], the other cheaper coinage metal (first of all Cu, but also Ag) species function as alternative catalysts for the selective activation of alkynylsulfones and their conversion to 3-sulfonylpyrroles. The developed catalytic annulation operates under relatively mild conditions (5 mol% of a coinage metal catalyst, DCE, 80 °C) and provides a high functional group tolerance (36 examples; yields up to 99%). The synthetic utility of the obtained products was illustrated by practical post-modification of either the pyrrole backbone, or the peripheral substituents. Coinage (Au, Ag, Cu) metal-catalyzed (3 + 2) annulation of α-aminoketones and electron-deficient alkynes provides a modular one-step route to a variety of 3-EWG-substituted pyrroles.