A New and Efficient Hypervalent Iodine−Benzyne Precursor, (Phenyl)[o-(trimethylsilyl)phenyl]iodonium Triflate: Generation, Trapping Reaction, and Nature of Benzyne

A new and efficient hypervalent iodine−benzyne precursor, (phenyl)[2-(trimethylsilyl)phenyl]iodonium triflate ( 10 ), is reported. The hypervalent iodine−benzyne precursor 10 is readily prepared by reaction of 1,2-bis(trimethylsilyl)benzene with a PhI(OAc) 2 /TfOH reagent system. Treatment of 10 with Bu 4 NF in CH 2 Cl 2 at room temperature gives high yields of the benzyne adducts in the presence of a trapping agent such as furan, 2-methylfuran, anthracene, tetraphenylcyclopentadienone, or 1,3-diphenylisobenzofuran. Especially, the result of the reaction in the presence of furan indicates a quantitative generation of benzyne and its efficient capture by the furan. Similarly, methylbenzynes ( 22 and 27 ) are efficiently generated from the corresponding methyl-substituted (trimethylsilyl)phenyliodonium triflates ( 12 and 13 ). The preparation of the hypervalent iodine−benzyne precursors, the generation of benzynes, the trapping reactions, and the nature are described in detail together with the advantages of the present reagents over the previously reported benzyne precursors.