Ethynyl-1,2-benziodoxol-3(1 H)-one (EBX): An Exceptional Reagent for the Ethynylation of Keto, Cyano, and Nitro Esters
Hot alkyne! The in situ generation of Ethynyl-1,2-BenziodoXol-3(1H)-one (EBX) from the corresponding silyl protected reagent using TBAF is reported. EBX displayed exceptional acetylene transfer ability to stabilized enolates, even at –78 °C. The mild reaction conditions allowed the first ethynylation reactions of linear keto, cyano and nitro esters in high yields to give all-carbon quaternary centers or non-natural amino acids after selective reduction of the nitro group.