Transition-Metal-Catalyst-Free Cross-Coupling Reaction of Secondary Propargylic Acetates with Alkenyl- and Arylboronic Acids

A cross-coupling reaction between secondary propargylic acetates and alkenylboronic acids proceeded to give 1,4-enynes in good yields without addition of transition metal catalyst and base. This simple protocol was also applicable to arylboronic acids, which gave 3-arylated alkynes in good yields. The observed induction period suggested that the reaction of propargylic acetates and organoboronic acids was affected by the in-situ generated AcOH as a catalyst, which was confirmed by a separate experiment.