Catalyst-Controlled Selective Alkylation/Cyclopropanation of Indoles with Vinyl Diazoesters.

A catalyst-controlled selective functionalization of indoles with vinyl diazoacetates has been developed. The use of gold catalysts exclusively leads to C3-alkylation products, whereas the highly diastereoselective cyclopropanation reaction is dominant for silver catalysis. Importantly, the gold and silver vinylcarbenes exhibit highly carbenic rather than vinylogous reactivity in these transformations.