Patent ID: 7816489

Claim:
A method for preparing a peptide or a pharmaceutically acceptable salt thereof, having oxytocin antagonist activity and consisting of a moiety A and a residue B having a C-terminal β-aminoalcohol which is bound to the moiety A by an amide bond, wherein (1) said residue B is: with Q being (CH 2 ) n —NH 2 , with n being 2, 3 or 4 and R being CH 3 or C 2 H 5 ; and (2) said moiety A is: with Mpa, Ile, Asn and Abu having the following meanings: Mpa 3-mercaptopropionic acid residue Ile isoleucine residue Asn asparagine residue Abu α-aminobutyric acid residue; with X being a D-aromatic α-amino acid, which may optionally have its side chain protected, and with Y being an aliphatic α-amino acid; which method includes the following steps: (a) reacting an α-amino acid having a protected amino side chain and an acylated α-amino group with a reducing agent to change the acyl group to an alkyl group and to simultaneously change the α-carboxy group to CH 2 OH to provide a diamino alcohol having the formula: wherein P 1 is H or an amino-protecting group; and Q′ is (CH 2 ) n —NP 2 P 3 , with n being 2, 3 or 4, P 2 being an amino-protecting group that is different from P 1 and not labile under conditions that would remove P 1 , and P 3 being H or an amino-protecting group that is the same or different than P 2 , provided however that P 2 and P 3 may be a divalent amino-protecting group; (b) reacting said product of step (a) with the pentapeptide: wherein P 4 , P 5 and P 6 are individually protecting groups to form the linear hexapeptide: c) selectively deprotecting and cyclizing the linear compound of step(b) to create the heptapeptide: