Patent ID: 6861528

Claim:
A method for the synthesis of 3-carboxymethylsulfinyl-7-fluoro-1-methyl-4-quinolone, comprising: a) providing: i) 3-cyanomethylthio-7-fluoro-1-methyl-4-quinolone; and ii) a first acid; b) reacting said 3-cyanomethylthio-7-fluoro-1-methyl-4-quinolone and said first acid under conditions such that 3-carboxymethylthio-7-fluoro-1-methyl-4-quinolone is produced; and c) reacting said 3-carboxymethylthio-7-fluoro-1-methyl-4-quinolone with; i) a second acid; and ii) a peroxide under conditions such that 3-carboxymethylsulfinyl-7-fluoro-1-methyl-4-quinolone is produced.