AbstractCyclic 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.