N-Sulfanylethylcoumarinyl amide (SECmide) peptide, which was initially developed for the use in the fluorescence-guided detection of promoters of N–S acyl transfer, was successfully applied to a facile and side reaction-free protocol for N–S acyl-transfer-mediated synthesis of peptide thioesters. Additionally, 4-mercapto benzyl phosphonic acid (MBPA) was proved to be a useful catalyst for the SECmide or N-sulfanylethylanilide (SEAlide)-mediated NCL reaction
