Useful Hypervalent Iodine Compound for the Introduction of an Ethynyl Group

1-[(Trimethylsilyl)ethynyl]-1,2-benziodoxol-3(1H)-one (TMS-EBX) is a mild ethynylating reagent for which various examples of ethynylations have been reported. For instance, in the presence of TBAF, TMS-EBX reacts with active methylene compounds such as 1,3-dicarbonyl compounds or α-nitro carbonyl compounds and an ethynylation proceeds at the methylene moieties.¹⁾ Furthermore, this reagent is applied to total synthesis of natural products and the synthesis of (-)-lingzhiol²⁾ and (+)-batzelladine³⁾ have been reported as examples. In this way, the ethynylation reaction using TMS-EBX can be applied for further chemical functionalization of ethynes and click chemistry, so that it is expected to be used widely.