Catalytic Three‐Component Synthesis of Conjugated Dienes from Alkynes via Pd0, PdII, and PdIV Intermediates Containing 1,2‐Diimine

Direct, efficient, selective, and catalytic all describe the synthesis of conjugated dienes from two molecules of alkyne, an organic halide, and tetramethyltin with 1 mol% of a (1,2-diimine)palladium complex in complex in DMF (see the catalytic cycle involving Pd0, PdII, and PdIV species on the right). Palladium–phosphane complexes do not catalyze this reaction. Furthermore, 1,4-dihalo-1,3-dienes were synthesized stoichiometrically from alkynes and molecular halogen.