Methanol → 90365-74-5

Temperature

30 °C

To a mixture of (3R,4R)-1-benzyl-3,4-dihydroxypyrrolidine-2,5-dione (44 g, 199 mmol, 1.0 eq) and THF (176 mL) at 20° C. (vessel jacket temperature) was added borane-tetrahydrofuran complex (1.0 mol/L) in THF (800 mL, 800 mmol, 1.0 mol/L, 4.0 eq) at a rate to maintain the temperature between 20° C. and 25° C. Over 1 hr, the jacket temperature was ramped to 60° C. and then held for 1 hr. Upon completion, the reaction was cooled to 30° C. and quenched by the slow dropwise addition of MeOH (97 mL, 12 eq) to the mixture at a rate to control off gassing. The reaction mixture was then heated to reflux and concentrated to a low stir volume. The reaction solvent THF was then replaced by a constant volume displacement with MeOH (total of 1.5 L). Once the THF content had been reduced to less than 1 wt %, MeOH was replaced by a constant volume displacement with EtOAc (total of 1.5 L) to reduce the MeOH content to less than 1 wt %. The total volume of EtOAc was then readjusted to about 250 mL (6 vol) and then cooled to 5° C. to crystallize the product. The desired product was isolated by filtration, washed with cold EtOAc (88 mL) and dried to give title compound (27.0 g, 140 mmol, 70%). A second crop of product was isolated by concentration of the combined filtrate and cake wash to half volume, which was then cooled to 5° C., filtered and washed with cold EtOAc (50 mL) to afford additional title compound (4.5 g, 23 mmol, 12%). 1H NMR (400 MHz, DMSO-d6) δ ppm 7.33-7.26 (m, 4 H) 7.25-7.20 (m, 1 H) 4.48 (d, J=4.8 Hz, 2 H) 3.38-3.31 (m, 2 H), 3.57 (d, J=13.0 Hz, 1 H) 3.46 (d, J=13.0 Hz, 1 H) 2.74 (dd, J=9.4, 5.9 Hz, 2 H) 2.30 (dd, J=9.4, 4.4 Hz, 2 H). m/z (EI+) for C11H15NO2 194.2 (M+H)+.

1. temperatureto maintain the temperature between 20° C. and 25° C
2. customwas ramped to 60° C.
3. waitheld for 1 hr
4. temperatureThe reaction mixture was then heated
5. temperatureto reflux
6. concentrationconcentrated to a low stir volume
7. temperaturecooled to 5° C.
8. customto crystallize the product

ORD record

ord-a570cf2477bc45a98e696de41b6d7cb7

Source dataset

uspto-grants-2016_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09290496B2