Palladium-catalyzed phosphine-, copper-free and aerobic Sonogashira coupling in aqueous media

A simple, highly efficient and phosphine-free protocol for the Sonogashira coupling of aryl iodides with terminal alkynes has been developed using Pd-2(dba)(3) (dba=dibenzylideneacetone) as the catalyst under aqueous, copper-free and aerobic conditions. The coupling of aryl iodides with aromatic terminal alkynes provided good to excellent yields and moderate to good yields were achieved using aliphatic terminal alkynes as one of the coupling partners. Aqueous ethanol as solvent is economical and environmentally benign in accordance with the concept of green chemistry.