δ-C–H alkynylation to synthesize various δ-alkynols from iminophenylacetic acids. The hypervalent iodine-coordinated benziodoxole-alkoxyl-iminophenylacetic acid complex was the key intermediate and was characterized by X-ray crystallography for the first time. δ-C–H alkynylation is compatible with sensitive functional groups, including azides, aldehydes, and free alcohols, for the synthesis of δ-alkynols