Patent ID: 7217835

Claim:
A method of producing a compound represented by the formula [I] or a salt thereof: wherein R 1 is each independently a halogen atom, an alkyl group, an alkoxy group or a hydroxy group, R 2 and R 3 are each independently a hydrogen atom or an amino-protecting group, R 4 an optionally substituted aryl group or an optionally substituted hetero ring group, and n is an integer of 0–4, provided that R 2 and R 3 are not simultaneously hydrogen atoms, wherein said method comprises reacting a compound represented by the formula [II] or a salt thereof: wherein R 1 , R 2 , R 3 and n are as defined above, with a compound represented by the formula [III] or a salt thereof: wherein R 4 is as defined above, and X is a halogen atom, a toluenesulfonyloxy group, a methanesulfonyloxy group or a trifluoromethanesulfonyloxy group, in the presence of an alkali metal alkoxide, in alcohol.