Catalytic activity of palladium acyclic diaminocarbene complexes in the synthesis of 1,3-diarylpropynones via Sonogashira reaction: cross- versus homo-coupling

Sonogashira cross-coupling of aryl acetylenes and aroyl chlorides catalyzed by palladium(II) acyclic diaminocarbene complexes was investigated. Reactions were carried out with 0.04 mol % of the catalysts, all of which demonstrated high stability and activity in air. The influence of the reaction conditions (temperature, time, amount of catalyst, solvent) and the structures of the starting compounds on the ratios of cross- (1,3-diarylpropynones) and homo-coupling (1,4-diarylbutadiynes) products was elucidated. The yields of 1,3-diarylpropynones reached 95–98%.