Formal [5+2] Cycloaddition of Vinyloxiranes with Oxazol‐5‐(4H)‐ones: A Facile Approach for Construction of Seven‐Membered Lactones

The formal [5+2] cycloaddition of vinyloxiranes with oxazol‐5‐(4H)‐ones proceeds readily at room temperature in THF in the presence of Pd2(dba)3·CHCl3, dppp, and K2CO3, thus furnishing the desired seven‐membered lactones in 67–96 % yield. The chemical structure of the title compounds was confirmed by X‐ray diffraction analysis. The formal [5+2] cycloaddition of vinyloxiranes with oxazol‐5‐(4H)‐ones proceeds readily at room temperature in THF in the presence of Pd2(dba)3·CHCl3, dppp, and K2CO3, thus furnishing the desired seven‐membered lactones in 67–96 % yield. The chemical structure of the title compounds was confirmed by X‐ray diffraction analysis.