Efficient coupling reagent for the synthesis of sterically hindered amides, especially peptides. In terms of reactivity and racemization-suppressing capability, this pyridinium-type reagent, BEP, proved to be more efficient than commonly used uronium- and phosphonium-type reagents, such as HBTU, BOP, and PyBroP, for the synthesis of hindered peptides containing N-methylated or Cα,Cα-dialkylated amino acid residues. BEP was also proven to be an efficient reagent for the synthesis of esters, especially active esters and hindered esters, and tert-butyl esters.