Large‐scale preparation of 13 C‐labeled 2‐(phenylthio)acetic acid and the corresponding labeled sulfoxides and sulfones

We have developed large‐scale efficient procedures for the conversion of commercially available [ 13 C]‐ or [ 2 H 3 , 13 C]methanol and 13 CO 2 or 13 C‐labeled bromoacetic acid to 2‐(phenylthio)[1,2‐ 13 C 2 ]‐, [1‐ 13 C]‐, and [2‐ 13 C]acetic acid. The resulting derivatives are versatile, chemically stable, and nonvolatile two‐carbon labeling precursors. We have used the 13 C‐isotopomers of 2‐(phenylthio)acetic acid in the synthesis of 13 C‐labeled acrylic acid, methacrylic acid, and trans ‐crotonic acid.