Rhenium-Catalyzed Regioselective ortho-Alkenylation and [3 + 2 + 1] Cycloaddition of Phenols with Internal Alkynes
Masahito Murai1, Masaki Yamamoto1, Kazuhiko Takai1
1Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , 3-1-1 Tsushimanaka, Kita-ku , Okayama 700-8530 , Japan.
Abstract:
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.
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