5-Nitro-2-pyridyl Diphenylphosphinate

[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

Peptide Synthesis.

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

1. Mukaiyama, T.; Kamekawa, K.; Watanabe, Y. CL 1981, 1367.

Alan Armstrong

University of Bath, UK

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