N-heterocyclic carbene-catalyzed cross-coupling of aldehydes with arylsulfonyl indoles.

3-(1-Arylsulfonylalkyl)indoles as electrophiles in the N-heterocyclic carbene-catalyzed umpolung reaction of aldehydes were realized for the first time. This intermolecular Stetter-type reaction features the commercially available catalyst and mild reaction conditions, providing alpha-(3-indolyl) ketone derivatives in high yields for a wide range of substrates.