Improved and Practical Synthesis of [2,4,5-Tris(trimethylsilyl)phenyl](phenyl)iodonium Triflate and Utilization as a 1,4-Benzdiyne Synthon

An efficient and improved method for preparing [2,4,5-tris(trimethylsilyl)phenyl](phenyl)iodonium triflate as a 1,4-benzdiyne synthon was developed by using phenyiodonium diacetate/boron triflouride center dot diethyl etherate [PhI(OAc)(2)/BF3 center dot OEt2] reagent. The iodonium triflate generated 3,4-bis(trimethylsilyl)benzyne quantitatively to give cycloadducts with tetraphenylcyclopentadienone, furan and anthracene in high yields. These cycloadducts bearing two trimethylsilyl groups were transformed into the corresponding aryne precursors, which underwent subsequent cycloaddition reactions to afford polycyclic aromatic compounds such as 1,4-dihydro-1,4-epoxyanthracene, naphthotriazole, triptycene, and anthratriazole derivatives in good to high yields. The total reactions are formally considered as double cycloaddition reactions of 1,4-benzdiyne. This practical and useful formal benzdiyne strategy is described.