With the insights gained from the computationally guided monomer down-selection, we synthesized a library of substituted furan-benzyne DA adducts. Treatment of obromofluorobenzene with magnesium turnings generated the Grignard reagent ofluorophenylmagnesium, which undergoes subsequent β-F elimination to generate benzyne as a transient intermediate, avoiding potentially dangerous benzyne concentrations (Figure ). Benzyne undergoes rapid DA with substituted furans to produce substituted 1,4dihydro-1,4-epoxynaphthalene (HEN) monomers in good to excellent yields (Figure ).