Method for producing peptides and their salts which have an agonist activity of luteinizing hormone releasing hormones secreted from the hypothalamus

Abstract

A peptide of the formula: 5-oxo—Pro—R1—Trp—Ser—R2—R3—R4—Arg—Pro—R6  (I) wherein R1 represents His, Tyr, Trp or p—NH2—Phe, R2 represents Tyr or Phe, R3 represents an optionally substituted Gly or an optionally substituted α-D-amino acid residue, R4 represents Leu, Ile or Nle, R6 represents (1) Gly—NH—R7, wherein R7 represents a hydrogen atom or an alkyl group which may optionally be substituted with a hydroxyl group, or (2) NH—R8, wherein R8 represents a hydrogen atom, an alkyl group which may optionally be substituted with a hydroxyl group or an ureido group (—NH—CO—NH2), is produced advantageously in an industrial scale by reacting a peptide of the formula: 5-oxo—Pro—R1—Trp—Ser—R2—R3—OH  (II) wherein R1, R2 and R3 have the same meanings as defined above or its salts, with a peptide of the formula: H—R4—R5—Pro—R6  (III) wherein R4 and R6 have the same meaning as defined above and R5 represents Arg which has been protected or its salts, to produce a peptide of the formula: 5-oxo—Pro—R1—Trp—Ser—R2—R3—R4—R5—Pro—R6  (I′) wherein R1, R2, R3, R4, R5 and R6 have the same meanings as defined above or its salt, and then subjecting thus obtained peptide (I′) to a de-protecting group reaction.

Dependencies are inferred from the claim text.