Compound library and method for producing compound library

An in vitro method for producing a compound library comprising two or more cyclic compounds represented by the formula (I):

• wherein
• m number of Xa, and Xb and Xc each independently represent an amino acid residue selected from the group consisting of any amino acids and analogs thereof,
• Z is present or absent and, when present, represents a peptide consisting of 1 to 100 amino acids and/or analogs thereof,
• m is an integer selected from 2 to 40,
• ring A is a nitrogen-containing 6-membered ring optionally having a substituent,
• B1 is an oxygen atom, a sulfur atom, or a NH group, and
• R1 is a hydrogen atom or a hydrocarbon group,
• the method comprising allowing a macrocyclase in vitro to act on two or more peptides represented by the formula (II):
• L
• ⁢
• P
• -
• X
• -
• (
• X
• ⁢
• a
• )
• m
• -
• Y
• -
• Z
• (
• II
• )
• wherein
• X represents a group represented by the formula (1):
• wherein
• R2 is a hydrogen atom or a hydrocarbon group,
• Y is a peptide residue consisting of four amino acids and/or analogs thereof and contains a group represented by the formula (2):
• wherein
• R1 and B1 are as defined above, and R3 represents a hydrogen or a hydrocarbon group,
• m number of Xa, m and Z are as defined above, and
• LP is present or absent and, when present, represents a peptide residue consisting of 1 to 100 amino acids and/or analogs thereof,
• and forming the nitrogen-containing 6-membered ring A while eliminating LP, if present, to form the two or more cyclic compounds represented by the formula (I).