A modular approach to α-arylated carbonyl compounds via indium tris(bistriflylamide)-catalyzed regioselective addition of β-ketoesters to 1,3-diynes

A modular synthesis of alpha-arylated carbonyl compounds has been achieved by the combination of an indium-catalyzed regioselective addition of P-keto esters to conjugated diynes and a palladium-catalyzed benzannulation reaction. Indium tris(bistriflylamide), In(NTf2)(3), was found to be an efficient catalyst for the first addition reaction of P-keto esters to diynes. The reaction proceeds with perfect regioselectivity to give conjugated enynes in high yield. The second palladium-catalyzed benzarmulation proceeds in high to excellent yield and with high regioselectivity for a variety of diynes. This two-step alpha-arylation of carbonyl compounds thus proceeds in a catalytic manner without loss of elements in the starting materials. The reaction may be performed in a single pot without isolation of the product of the first step.