A combination of fluorobenziodoxole (FBX) and BF3 . OEt(2)in cyclopentyl methyl ether promotes regio- and stereoselective addition of benziodoxole and methoxy groups to alkynes. This difunctionalization reaction tolerates a variety of functionalized internal and terminal alkynes to affordtrans-beta-alkoxyvinylbenziodoxoles, which represent versatile precursors to stereochemically well-defined multisubstituted vinyl ethers. The reaction is proposed to involve cleavage of the I-F bond of FBX by BF3, followed by electrophilic activation of the alkyne by the resulting cationic I(III)species that triggers the nucleophilic addition of the ethereal oxygen.