American Chemical Society Acta Medica Okayama 15237060 21 9 2019 Rhenium-Catalyzed Regioselective ortho-Alkenylation and [3 + 2 + 1] Cycloaddition of Phenols with Internal Alkynes 3441 3445 EN Masahito Murai Graduate School of Natural Science and Technology, Okayama University Masaki Yamamoto Graduate School of Natural Science and Technology, Okayama University Kazuhiko Takai Graduate School of Natural Science and Technology, Okayama University An operationally simple and direct rhenium-catalyzed ortho-alkenylation (C-alkenylation) of unprotected phenols with alkynes was developed. The protocol provided ortho-alkenylphenols exclusively, and formation of para- or multiply alkenylated phenols and hydrophenoxylation (O-alkenylation) products were not observed. The [3 + 2 + 1] cycloaddition of phenols and two alkynes via ortho-alkenylation was also demonstrated, in which the alkynes functioned as both two- and one-carbon units. These reactions proceeded with readily available starting materials under neutral conditions without additional ligands. No potential conflict of interest relevant to this article was reported.