Diisopropylethylamine → HCID 58386810, compound

Temperature

75 °C

To a solution of (3aR,7aS)-5-benzyl 3-tert-butyl 2-oxotetrahydrooxazolo[4,5-c]pyridine-3,5(2H,6H)-dicarboxylate in a mixture of EtOH and EtOAc (1:1, 0.07 M) was added Pd/C (10% by weight) and the reaction was stirred under a hydrogen balloon for 15 h. The solution was then filtered through a pad of Celite and the filtrate was concentrated to dryness to give a clear oil. To a solution of (3aR,7aS)-tert-butyl 2-oxohexahydrooxazolo[4,5-c]pyridine-3(2H)-carboxylate in i-PrOH (0.12 M) was added 4-chloro-3-nitropyridine (1.2 equiv.) and DIEA (4.0 equiv.) The reaction was heated to 75° C. for 2 h, then cooled to room temperature and concentrated under vacuo. The crude mixture was diluted with EtOAc, water was added, the organic layer was extracted, washed with brine, dried with Na2SO4, and concentrated. The crude was purified via silica gel column chromatography eluting with EtOAc (100%) to yield (3aR,7aS)-tert-butyl 5-(3-nitropyridin-4-yl)-2-oxohexahydrooxazolo[4,5-c]pyridine-3(2H)-carboxylate as a yellow foam in 89% yield). LCMS (m/z): 365.1 (MH+), Rt=1.79 min.

1. filtrationThe solution was then filtered through a pad of Celite
2. concentrationthe filtrate was concentrated to dryness
3. customto give a clear oil
4. temperaturecooled to room temperature
5. concentrationconcentrated under vacuo
6. additionThe crude mixture was diluted with EtOAc, water
7. additionwas added
8. extractionthe organic layer was extracted
9. washwashed with brine
10. dry with materialdried with Na2SO4
11. concentrationconcentrated
12. customThe crude was purified via silica gel column chromatography
13. washeluting with EtOAc (100%)

ORD record

ord-d9c4a3c9a4994f94b372f55569d471f8

Source dataset

uspto-grants-2012_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08168794B2