1-(ORGANOSULFONYLOXY)-3(1H)-1,2-BENZIODOXOLES - PREPARATION AND REACTIONS WITH ALKYNYLTRIMETHYLSILANES

Organosulfonyloxy derivatives of 1,2-benziodoxol-3(1H)-one (3a-c) and 3,3-bis(trifluoromethyl)-3(1H)-1,2-benziodoxole (5a-c) can be prepared in high yield by the reaction of 1-hydroxybenziodoxoles 1 or 4 and th e corresponding sulfonic acids or Me(3)SiOTf in the form of stable, bu t moderately hygroscopic, microcrystalline solids. Reaction of the tri flate derivatives 3a and 5a with alkynyltrimethylsilanes affords eithe r alkynyliodonium triflates 6, or -beta-(trifluoromethanesulfonyloxy)a lkenyliodonium triflates 7, while the same reaction in the presence of pyridine selectively gives the respective 1-alkynylbenziodoxoles 8 an d 9 in 82-90% yield.