No abstract

Condensates of some 2-hydroxyaryl ketones with protein amino acids have been prepared. The reaction has been shown to proceed without racemization and the derivatives have been isolated as free acids. Their unusual stability is ascribed to the presence of a strong intramolecular hydrogen bond. The N-arylmethylene function is cleaved under mild conditions of acid hydrolysis. Ketimines derived from D-phenylglycine decarboxylate at room temperature.

Nα-t-Butoxycarbonyl-Nε-(2-hydroxyarylmethylene)-ornithine and -lysine have been synthesized and coupled with amino acyl resins in the presence of dicyclohexylcarbodiimide to form N-protected peptide resin esters. The ketimine protecting group was found to be stable under anhydrous conditions and the urethane blocking group could be removed preferentially. A number of lysine- and ornithine- containing peptides have been synthesized by the solid-phase technique.