Regioselective Synthesis of Functionalized Pyrroles via Gold(I)-Catalyzed [3+2] Cycloaddition of Stabilized Vinyl Diazo Derivatives and Nitriles

The reaction of nitriles with alkenyldiazo compounds in the presence of gold catalysts provides functionalized pyrrole derivatives in moderate to high yields. This formal [3+2] cyclization reaction takes place with complete regioselectivity. The observed regiochemical outcome suggests the attack of the nitrile to the terminal position of the alkenylgold carbenoid (vinylogous reactivity). A broad range of nitriles (including those bearing functional groups) is compatible with this cyclization reaction.