Improved synthesis and aminoacylation of p-nitrobenzophenone oxime polystyrene resin for solid-phase synthesis of protected peptides.

Procedures for the synthesis and acylation of p-nitrobenzophenone oxime polystyrene resin for the preparation of protected peptide segments have been reexamined. Friedel-Crafts acylation with p-nitrobenzoyl chloride is complete in less than one hour at room temperature. Conversion of the ketoresin to the corresponding oxime requires less than six hours at 85 degrees C. Carbodiimide-mediated coupling of tert-butyloxycarbonyl-amino acids to the oxime resin requires less than one hour. By varying the quantity of p-nitrobenzoyl chloride and aluminum chloride used for acylation, the oxime substitution level of the resulting resin can be controlled between 0.2 and 0.8 milliequivalents per gram of resin. Aminoacyl oxime resin can thus be prepared in one day.