An ICl-mediated highly chemo-and regioselective functional group interconversion from methyl homopropargyl ether to α-iodo-γ-chloroketone is reported. Density functional theory (DFT)-calculated reaction coordinate and potential energy surface support the high chemo-selectivity observed for the formation of α-iodo-γ-chloroketone over furan. The fivemembered oxonium ring formation−ring opening mechanism is a potential template for the preparation of polyfunctionalized carbonyl compounds.