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ChemicalBook CAS DataBase List Methyl (R)-(+)-lactate
17392-83-5

Methyl (R)-(+)-lactate synthesis

10synthesis methods
Methyl lactate

547-64-8

L(+)-Lactic acid

79-33-4

Methyl (R)-(+)-lactate

17392-83-5

The general procedure for the synthesis of L-lactic acid and D-lactic acid methyl ester from methyl lactate was as follows: in a standard 500-μL hydrolysis reaction system, 140 μg of purified esterase PHE14, 50 mmol/L of racemic methyl lactate as substrate, and 50 mmol/L of phosphate buffer (pH 7.5) were added. The reaction system was incubated at 37°C for 1 hour. Upon completion of the reaction, the reaction samples were extracted using an equal volume of ethyl acetate, and the organic phase was subsequently analyzed to assess the enzymatic disassembly of (±)-lactic acid methyl ester.

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Yield: 88.2 % ee

Reaction Conditions:

Stage #1:bis(1,5-cyclooctadiene)rhodium(I) trifluoromethanesulfonate;(R)-N-diphenylphosphino-N-methyl-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine in tetrahydrofuran at 25; for 0.25 h;
Stage #2:pyruvic acid methyl ester with hydrogen in tetrahydrofuran under 1277.21 - 1794.37 Torr; for 6 h;Product distribution / selectivity;

Steps:

18 Methyl Lactate using the Rhodium Complex of Ligand 4a
Methyl pyruvate (51 mg; 0.50 mmol) was dissolved in a reaction vessel in anhydrous THF (3.0 mL) and degassed with argon for 15 minutes. Bis(1,5-cycloocta-diene)rhodium trifluoromethanesulfonate (2.3 mg; 5 μmol; 0.01 equiv) and ligand 4a from Example 1 (3.7 mg; 6 μmol; 0.012 equiv) were combined and argon-degassed anhydrous THF (2.0 mL) was added. This solution was stirred at 25° C. under argon for 15 minutes and then added to the solution of 2-acetamidocinnamic acid. The resulting solution was then flushed with hydrogen and pressurized to 0.69-1.38 bars gauge (10-20 psig) hydrogen. The reaction mixture was stirred for 8 hours to afford 90.2% conversion to methyl (R)-lactate with 88.2% ee as determined by chiral GC analysis. The analytical properties of methyl lactate were identical to an authentic sample.Chiral GC [Cyclosil-B (J&W Scientific) 30 m×0.25 mm ID, film thickness 0.25 μm, 75° C. isothermal, 15 psig He]: tR[methyl (R)-lactate] 7.75 min, tR[methyl (S)-lactate] 9.16 min. tR(methyl pyruvate) 5.16 min.

References:

Eastman Chemical Company US6906213, 2005, B1 Location in patent:Page/Page column 15

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