Method for producing amino acid derivatives

A method for producing a compound represented by the formula (1):

• wherein LG is a leaving group, PG1 is an amino-protecting group, and R is a hydrocarbon group having 1-8 carbon atoms and optionally having substituent(s),
• comprising
• reacting a compound represented by the formula (6):
• with an amino group protecting agent to obtain a compound represented by the formula (7):
• wherein each symbol is as defined above, or a salt thereof;
• reacting the aforementioned compound represented by the formula (7) with a lactonization agent to obtain a compound represented by the formula (8):
• wherein each symbol is as defined above;
• reacting the aforementioned compound represented by the formula (8) with an esterification agent to obtain a compound represented by the formula (9):
• wherein each symbol is as defined above;
• and
• reacting the aforementioned compound represented by the formula (9) with a leaving group introduction agent.