Patent ID: 7910752

Claim:
A method for preparing a compound of formula (III): wherein R is C 1 -C 6 alkyl, comprising reacting a compound of formula (I): with a compound of formula (II): wherein R is the same as defined for the formula (III) above and X 1 and X 2 are each independently a halogen atom, in the presence of at least one base selected from the group consisting of pyridine, DMAP (4-dimethylaminopyridine), quinoline, isoquinoline, triethylamine, diisopropylethylamine, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), DBN (1,5-diazabicyclo[4.3.0 ]non-5-ene), sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, and sodium bicarbonate.