Chemical Racemization of Methyl L-ß-Acetylthioisobutyrate.

Methyl L-ß-acetylthioisobutyrate was racemized with 1,8-diazabicyclo-[5.4.0]-undecene-7 as a catalyst. Methyl methacrylate and thioacetic acid were identified as the intermediates of the reaction. Thioacetic acid was relatively unstable and susceptible to decomposition during the racemization process. The addition of excess methyl mechacrylate to the reaction mixture prevented a decrease of the racemate. The racemized ester was confirmed to be usable as a substrate for the enzymatic production of D-ß-acetylthioisobutyric acid.