A 2-Benzothiazolylphenyl Group Accelerates the Intramolecular [2+2] Cycloaddition of Allene-Ynes

A [2+2] cycloaddition reaction of allene‐ynes under thermal conditions with/without a metal complex is described. A key feature of this reaction is that a 2‐benzothiazolylphenyl group bearing a CC triple bonds remarkably promotes the reaction to give the corresponding cyclobutenes with or without metal catalysts. A [2+2] cycloaddition reaction of allene‐ynes under thermal conditions with/without a metal complex is described. A key feature of this reaction is that a 2‐benzothiazolylphenyl group bearing a CC triple bonds remarkably promotes the reaction to give the corresponding cyclobutenes with or without metal catalysts.