[80944-63-4] · C17H13N2O4P · 5-Nitro-2-pyridyl Diphenylphosphinate · (MW 340.29)
(reagent for peptide synthesis1)
Physical Data: mp 125-127 °C.
Preparative Method: from diphenylphosphinyl chloride and 2-hydroxy-5-nitropyridine in the presence of Triethylamine.1
Tetrabutylammonium salts of N-protected amino acids can be coupled with amino acid methyl or ethyl esters in the presence of 5-nitropyridyl diphenylphosphinate (1).1 Reaction between tetrabutylammonium N-benzoyl-L-leucinate and glycine ethyl ester hydrochloride (Young test) proceeded with little racemization (98% L-isomer) (eq 1). The 2-hydroxy-5-nitropyridine byproduct is water soluble and so is easily separated from the dipeptide. Protection of side-chain functionality such as aliphatic or phenolic hydroxyl groups or imidazole or indole rings is unnecessary.
Using pyridine as solvent, the method was applied to the one-pot cyclization of linear peptides, including the synthesis of gramicidin S (eq 2).1
University of Bath, UK