Patent ID: 7189847

Claim:
A process for producing a compound represented by the formula (VI-a): which comprises reacting a compound represented by formula (III-1-a): or a compound represented by the following formula with a metal borohydride compound in an aprotic solvent in the presence of an alcohol to give a compound represented by formula (IV-a): reacting this compound with a compound represented by the following formula under basic conditions: to give a compound represented by formula (V-a): and then treating this compound under basic conditions; wherein, in the above formulae, X 1 , X 2 and X 3 each independently represents a halogen atom; R 3 represents a hydrogen atom or a carboxyl-protective group; R 5 and R 6 each independently represents an alkyl group having 1 to 6 carbon atoms; R 7 represents a carboxyl-protective group; and Y represents an alkoxy group having 1 to 6 carbon atoms, a halogen atom or a dialkylamino group (wherein the alkyl groups may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms).