Patent ID: 7189857

Claim:
A method for production of a compound represented by the general formula (VI): wherein R 1 is an optionally substituted lower alkyl, an optionally substituted aryl, an alkynyl, or an optionally substituted heteroaryl, and Y is an optionally substituted alkyl, the method comprising the step of: treating a compound represented by the general formula (II-A) or the general formula (II-B) with thionyl chloride as follows: wherein R 1 is as described above; R 2 is a lower alkyl, an optionally substituted aralkyl, or an optionally substituted heteroarylalkyl: and R 3 is a lower alkyl; subjecting the obtained compound represented by the general formula (I-A) or the general formula (I-B) to a hydrolysis as follows: and subjecting the obtained compound represented by the general formula (III-A) or the general formula (III-B) to a peptide bond formation.