Palladium(II)-Catalyzed Cascade Reactions of Ene-Ynes Tethered to Cyano/Aldehyde: Access to Naphtho[1,2-b]furans and Benzo[g]indoles.

An efficient palladium(II)-catalyzed cascade reaction of ene-yne substrates carrying cyano/aldehyde group is described. It involves successive hetero- and benz-annulations in one pot via trans-oxo/aminopalladation onto alkyne, followed by 1,2-addition to cyano/aldehyde, providing a convenient synthesis of both naphtho[1,2-b]furans and benzo[g]indoles. The reaction constitutes a fast intramolecular assembly through several carbon-carbon and carbon-heteroatom bond formations taking place in one pot. The reactions are operationally simple, compatible with a range of functional groups and atom-economical in nature.