Increased amounts of d-enantiomer dependent on alkaline concentration in the synthesis of l-[methyl-11C]methionine

✍ Scribed by Kiichi Ishiwata; Tatsuo Ido; Willem Vaalburg

• Book ID: 103920057
• Publisher: Elsevier Science
• Year: 1988
• Weight: 205 KB
• Volume: 39
• Category: Article
• ISSN: 0883-2889
• DOI: 10.1016/0883-2889(88)90021-4

✦ Synopsis

The presence of D-enantiomer in L-[methyl-ttC]methionine prepared from [HC]CH3I and L-homocysteine thiolactone, was measured by high performance liquid chromatography using a reverse-phase column with an eluent containing L-proline and cupric acetate. The amount of D-enantiomer increased with concentration of NaOH used. The reaction time, 2-10 min, and the reaction temperature, 4ff 80~C, have only minor effect on the formation of D-enantiomer. No significant difference was found for three different lots of L-homocysteine thiolactone. At the highest concentration investigated, 1.0 M NaOH in 50% aqueous acetone, the percentage of D-enantiomer was found to be 7.7%. With 0.025 M NaOH used only 2.1% was measured. When L-[methyl-HC]methionine was incubated in 1.0 M NaOH, no conversion of L-into D-enantiomer was observed.