A convenient method for the preparation of 2,5-dihydrofurans by using the chemistry of alkynyl(phenyl)iodonium salts is reported. Treatmentof 3-alkoxy-1-alkynyl(phenyl)iodonium triflates with sodium benzenesulfinate generates an alkylidenecarbene, which undergoes [1,5]-C-H insertionto form 2-substituted 4-benzenesulfonyl-2,5-dihydrofurans in reasonable yield. These cyclic vinyl sulfones are functionalized in such a way asto make them useful starting materials for the preparation of lignans. The application of this methodology to the first total synthesis of(±)-magnofargesin is disclosed.
