Synthesis of Arginine Peptides with N7,N8-(1,2-Dihydroxycyclohex-1,2-ylene)-Protection. Studies on the Reaction of 1,2-Cyclohexanedione with Arginine and Lysine

Article abstract of DOI:10.1007/BF00799922

A method for the synthesis of arginine peptides is described, in which the side chain guanidine function is blocked through reaction with 1,2-cyclohexanedione in borate buffers.Coupling to the carboxyl group of arginine was achieved by active ester, by dicyclohexylcarbodiimide/1-hydroxybenzotriazole, and by the mixed anhydride methods.Neither lactam formation nor acylation of the vicinal hydroxyls of the N⁷,N⁸-(1,2-dihydroxycyclohex-1,2-ylene) guanidino group was observed.Removal of the protecting group is strongly influenced by steric factors.Some side reactions obs erved during modification of peptides and protein fragments with 1,2-cyclohexanedione are also described. - Keywords: Activation, lactam-formation, side-reactions; N⁷,N⁸-(1,2-Dihydroxycyclohex-1,2-ylen)-arginine-derivatives and -peptides; Semisynthesis.