Nickel–palladium-catalyzed hydroamination/cyclization of sulfur-substituted 1,6-diynes with secondary amines

Hydroamination/cyclizations of sulfur-substituted 1,6-diynes catalyzed by nickel or nickel–palladium in DMSO were examined. Pyrroles 2a–l and furans 5a–i bearing various secondary amines were obtained in high yields. The organosulfanylmethyl group on pyrroles was easily oxidized with ceric ammonium nitrate to produce the pyrrolecarboxaldehyde and corresponding acetal.