Abstract

S. Abdel Rahmam and A. Hattaba

The photosensitive 3-nitro-4-bromometylbenzoyl polyethylene glycol support was prepared for use in the liquid phase method (LPM) of peptide synthesis by coupling the polymer with 3-nitro-4-bromomethy-benzoyl chloride instead of the coupling with 3-nitro-4-bromomethybenzoic acid which raised the yield of coupling from 60% to 85.8%. The produced photosenitive polymer was esterified with potassium salts of different Boc amino acids using 18-crown-6 as catalyst in different time, temperatures* molar ratios of reactants and solvents. Preliminary results using 2.0 equivelants each of 18-crown-6, the potassium salt of Boc amino acid and 0.5 equivalent of the polymer at RT for 18 hrs. resulted in virtually complete esterification in DMF. These modifications in the synthesis of the photosensitive polymer support and in its esterification reaction with the 1st Boc amino acid avoid side reactions and raise the yield of the final peptide.

Improved; Bromomethylbenzoyl

[ View HTML Full Text]