Cornforth reagent → 1-tert-Butyl 2-methyl (2R)-4-oxopyrrolidine-1,2-dicarboxylate

To slurry of pyridinium dichromate (9.97 g, 26.5 mmol) in dichloromethane (60 mL) at rt was added (2R,4R)-1-tert-butyl 2-methyl 4-hydroxypyrrolidine-1,2-dicarboxylate (5.00 g, 20.39 mmol) in several portions. The resulting mixture was stirred overnight at rt. Celite (5 g) was added and the mixture stirred for 40 min, filtered and the filter cake was rinsed with additional dichloromethane (50 mL×3). The resulting filtrate was concentrated and toluene (40 mL) was added followed by concentration again under vacuum to give ˜6.5 g of a brown syrup as the crude product. Purification by flash silica gel chromatography (120 g column, EtOAc in hexane, 0 to 100% gradiant, 85 mL/min) afforded 4.18 g (84%) of the title compound as a white solid. LCMS (condition A): m/z 144 (M-Boc) −ve. 1H NMR (400 MHz, CDCl3) δ ppm 4.64-4.89 (1 H, m), 3.84-3.96 (2 H, m), 3.77 (3 H, s), 2.81-3.10 (1 H, m), 2.59 (1 H, dd, J=18.93, 1.76 Hz), 1.52 (9 H, s).

1. additionCelite (5 g) was added
2. stirringthe mixture stirred for 40 min
3. filtrationfiltered
4. washthe filter cake was rinsed with additional dichloromethane (50 mL×3)
5. concentrationThe resulting filtrate was concentrated
6. additiontoluene (40 mL) was added
7. concentrationfollowed by concentration again under vacuum

ORD-Eintrag

ord-d603aa3ad0c54346afc880545fa3cc32

Quelldatensatz

uspto-grants-2015_12

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US09221826B2