Abstract: | Cyclic peptides containing sarcosine, cyclo-(Pro-Sar-Gly)2, cyclo-(Sar-Sar-Gly)2, cyclo-(Sar4), and cyclo-(Sar6) have been synthesized by the cyclization of the p-nitrophenyl ester of linear peptides. The tert-butoxycarbonyl group was used as the Nα-protecting group, which was removed by acid. Benzyl ester was used to protect the C-terminal. tert-butoxycarbonylpeptide was obtained by the stepwise elongation of the peptide bond by the carbodiimide method. Deblocking and cyclization of the linear peptides gave the cyclic peptides. |