Patent ID: 7205402

Claim:
A process for the synthesis of a compound of formula (III): said process comprising: (1) contacting a compound of formula (I): or a salt thereof, with C 1-6 alkyl chloroformate in the presence of a first base, in a solvent, at a temperature of about 20–56° C., under ambient atmosphere, to give a compound of formula (II) wherein R is C 1-6 alkyl; wherein the first base is K 2 HPO 4 ; wherein the solvent is selected from the group consisting of THF, MeTHF, ethyl acetate, n-butyl acetate, isopropyl acetate, methyl t-butyl ether (MTBE), toluene, xylenes, acetonitrile, acetone, methanol, ethanol, and isopropanol; (2) separating organic layer and concentrating to obtain the compound of formula (II) in solution; and (3) contacting the compound of formula (II) in solution with a second base NaOH at about 47–52° C. to obtain the compound of formula III.