TETRAFLUOROBORIC ACID, A USEFUL DEPROTECTING REAGENT IN PEPTIDE SYNTHESIS

Abstract

We have found that tetrafluoroboric acid (HBF₄) in trifluoroacetic acid (TFA) in the presence of thioanisole cleaves various protecting groups currently used in peptide synthesis. HBF₄ in TFA cleaves an amino acid amide from 4-methylbenzhydrylamine resin more effectively than trifluoromethanesulfonic acid in TFA. Lamprey gonadotropin-releasing hormone (a 10-residue peptide amide) was synthesized using 1 M HBF₄-thioanisole in TFA by both solution-phase and solid-phase methods.