Abstract: Cyclic compounds and oligopeptide compounds that selectively inhibit KRAS were found. Oligopeptide compounds and non-natural amino acids useful for producing a cyclic compound were also found. Moreover, cyclic compounds and oligopeptide compounds were found to interact with an amino acid residue specific to KRAS.

Abstract: The present inventors found cyclic peptide compounds that interact with Ras, and pharmaceutical compositions containing the cyclic peptide compounds or salts thereof, or solvates thereof.

Abstract: Solid-phase synthesis of a peptide has a problem that a desired elongation reaction is prevented from proceeding by diketopiperazine and a 6-membered diamine skeleton compound formed when a protective group at the N-terminal is removed. The present inventors have found that when in production of a peptide by a solid-phase method, a peptide in which an amino group at the N-terminal is protected with a protective group having an Fmoc skeleton is treated in a specific solvent with a base having a pKa of 23 or more in acetonitrile as a conjugate acid, and a peptide chain is then elongated, it is possible to solve the problem described above.

Abstract: The present inventors found cyclic peptide compounds that interact with Ras, and non-natural amino acids useful for the production of the cyclic peptide compounds. The inventors also found that the cyclic peptide compounds inhibit the binding between Ras and SOS. In addition, the inventors found specific non-natural amino acids contained in the cyclic peptide compounds and methods for production thereof.