Synthesis of o-Allyloxy(ethynyl)benzene Derivatives by Cu-Catalyzed Suzuki-Miyaura-Type Reaction and Their Transformations into Heterocyclic Compounds

We have found that Suzuki-Miyaura-type reactions of o-allyloxy(bromoethynyl) benzenes with arylboronic acids using a hydrazone/Cu catalyst system proceeded smoothly in iPrOH under mild conditions to afford the corresponding o-allyloxy(arylethynyl) benzene derivatives in good yields without de-composition of the allyloxy group. We have further demonstrated that annulation and enyne metathesis of the o-allyloxy(arylethynyl) benzene derivatives using transition-metal catalysts led to various heterocyclic compounds.