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 Bu4NF in CH2Cl2 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 trappings reactions, and the nature are described in detail together with the advantages of the present reagents over the previously reported benzyne precursors.