C[O:2][C:3](=[O:10])[CH2:4][C:5](=[CH2:9])[C:6]([OH:8])=[O:7].[H][H].[CH3:13]OC(=O)C[C@@H](C)C(O)=O>CO>[CH3:13][O:8][C:6](=[O:7])[CH:5]([CH3:9])[CH2:4][C:3]([OH:2])=[O:10]133 mg (0.182 mmol) of (RophosARhCOD)CF3SO3 (=precatalyst) were introduced under protective gas into 21 ml of methanol in a 4 l (enamel) Pfaudler autoclave and 526 g (3-65 mol) of 2-methylenesuccinic acid 4-monomethyl ester (=substrate) dissolved in 704 ml of methanol were added. Hydrogenation was then carried out at 40° C. under 5 bar of hydrogen. Conversion of the substrate was complete after 4 h (1H-NMR, 500 MHz). The enantiomeric excess of the product (2R)-methylsuccinic acid 4-monomethyl ester was determined by gas chromatography to be >98% (from: BGB-Analytik, column type: BGB-174, length: 30 m, internal diameter: 0.25 ml, film thickness: 0.25 μm, carrier gas: helium, inlet pressure: 2.35 bar, temperature: 135° C., heating rate: 1.2° C./min, retention time of R enantiomer: 23.3 min, retention time of S enantiomer: 22.6 min). The s/c ratio was 20 000:1.
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