Di-benzoyl-d-tartaric acid → dibenzoyl-D-tartrate

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Reaction Steps

A 12 L, 4-neck, flask was fitted with a mechanical stirrer, temperature probe and then charged with dibenzoyl-D-tartaric acid (189.7 g) and methanol (5.5 kg) under an atmosphere of nitrogen. Example 53 (126.3 g) was dissolved in methanol (1.48 kg) in a separate flask. A portion of the solution (13.5%) of Example 53 in methanol was added over a period of 1 hour to the dibenzoyl-D-tartrate/methanol solution. The solution was then seeded (seed crystals are prepared as described below) with product (250 mg). The remainder of the Example 53 solution was added over 7.5 hours. A rinse of methanol (278 mL) was employed to wash any remaining starting material residue from the 2 L Erlenmeyer flask, and the resultant mixture was pumped into the reaction vessel over 1 hour. The reaction was allowed to proceed for 14 hours. The suspension was filtered, washed with tert-butyl methyl ether (0° C., 2 L) and dried under vacuum to provide the title compound as the dibenzoyl-D-tartrate. The product exhibited an ee of 98.2%, as judged by reverse phase chiral HPLC analysis [Method: Isocratic elution: 70% aqueous (with 5 mM phosphate buffer, pH 6.9): 30% acetonitrile for 15 minutes. Column: Chiralpak® AS-RH (4.6 mm×150 mm) Temperature 35° C. The wavelength that is used for calculations was 210 nm.]. The salt was freebased by the addition of ethyl acetate (1 L) and extraction with 15% aqueous K3PO4 (600 mL) twice. The combined basic aqueous layers were then extracted with ethyl acetate (500 mL). The combined organic layers were then extracted with 20% brine (500 mL) twice. The title compound was obtained by evaporation of the organic layer under vacuum (47.5 g). 1H NMR (500 MHz, DMSO-d6) δ ppm 8.12 (s, 1H), 7.81 (d, J=2.0 Hz, 1H), 7.49 (dd, J=2.5, 8.0 Hz, 1H), 7.18 (d, J=8.0 Hz, 1H), 3.26 (m, 1H), 3.20 (m, 1H), 3.11 (m, 1H), 3.08 (m, 1H), 2.84 (dd, J=9.0, 10.5 Hz, 1H), 2.62 (m, 2H), and 2.18 (m, 1H); MS (ESI+) m/z 251 [M+H]+.

Provenance & Evidence