Regio- and Enantioselective Synthesis of Dihydropyrido[1,2- a ]indoles via Catalytic Asymmetric Annulative Allylic Alkylation.

A palladium-catalyzed asymmetric annulative allylic alkylation reaction of 2-[(1 H -indol-2-yl)methyl]malonates with ( E )-but-2-ene-1,4-diyl dicarbonates is described, leading to the regio- and enantioselective synthesis of dihydropyrido[1,2- a ]indoles with a chiral cyclic allyl stereocenter adjacent to the ring-junction nitrogen atom in moderate to good yields. The salient features of this protocol include mild conditions, a broad substrate scope, and good compatibility with substituents as well as high regio- and stereoselectivities, providing a catalytic asymmetric entry for fabricating chiral pyridoindole scaffolds.