Sodium Carbonate → HCID 117977145, compound

To a crude 5:1 mixture of rac-(3R,4S)-4-aminotetrahydro-2H-pyran-3-ol and rac-(3R,4S)-3-aminotetrahydro-2H-pyran-4-ol (see Example 8, 3.50 g, 29.9 mmol) in 150 mL of water at 0° C. was added sodium carbonate (3.80 g, 35.9 mmol) followed by benzyl chloroformate (5.12 mL, 35.9 mmol) dropwise. After 30 min, the mixture was warmed to rt, and after 4 h, a solid precipitate was collected via filtration and recrystallized from ethyl acetate/hexanes to provide benzyl[(3R,4S)-3-hydroxytetrahydro-2H-pyran-4-yl]carbamate that gave a proton NMR spectra consistent with theory. The filtrate was concentrated and the resultant residue was subjected to purification via silica gel chromatography, eluting with 30-70% ethyl acetate in hexanes to provide a mixture of benzyl[(3R,4S)-3-hydroxytetrahydro-2H-pyran-4-yl]carbamate and benzyl [(3S,4R)-3-hydroxytetrahydro-2H-pyran-4-yl]carbamate. The two enantiomers were separated via chiral chromatography to provide pure benzyl[(3R,4S)-3-hydroxytetrahydro-2H-pyran-4-yl]carbamate and benzyl[(3S,4R)-3-hydroxytetrahydro-2H-pyran-4-yl]carbamate. The semi-preparative separation was performed on a 5 cm id by 50 cm length, 20 μm, AD column run at 85 mL/min in a mixture of 60% ethanol/40% heptane with 0.1% DEA added to both components.

1. waitafter 4 h
2. filtrationa solid precipitate was collected via filtration
3. customrecrystallized from ethyl acetate/hexanes

ORD record

ord-8b6d241e14694abd8ff482a6f8d143b4

Source dataset

uspto-grants-2014_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08754220B2