Isocyanatocarbonyl chloride → 8-phenyl-7,8-dihydropyrano[3,4-e][1,3]oxazine-2,4(3H,5H)-dione

HRID 475773Notes

Reaction equation

[C:1]1([CH:7]2[C:12](=[O:13])[CH2:11][CH2:10][O:9][CH2:8]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[C:14](Cl)([N:16]=[C:17]=[O:18])=[O:15]>CCOC(C)=O>[C:1]1([CH:7]2[C:12]3[O:13][C:17](=[O:18])[NH:16][C:14](=[O:15])[C:11]=3[CH2:10][O:9][CH2:8]2)[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1

Participants

Conditions

Temperature: 58 °C

Procedure

A mixture of 3-phenyldihydro-2H-pyran-4(3H)-one (Intermediate I(2)) (3 g, 17.02 mmol) and carbonisocyanatidic chloride (10.48 g, 29.8 mmol) in a sealed tube was heated to 58° C. and stirred for 1 h. The mixture was then brought to 130° C. and stirred for an additional 2 h. The reaction turned black during this time. After cooling to RT, the tar was taken up in EtOAc (100 mL). The resulting solution was washed with saturated aqueous sodium bicarbonate (2×50 mL), brine (50 mL), dried over MgSO4, filtered and concentrated in vacuo. Purification by flash chromatography (Silica, EtOAc/Hexanes) gave 8-phenyl-7,8-dihydropyrano[3,4-e][1,3]oxazine-2,4(3H,5H)-dione (2.58 g, 10.52 mmol, 61.8% yield) as a brown solid. LC-MS (M+H)+=246.0. 1H NMR (500 MHz, MeOD) δ ppm 7.34-7.41 (4H, m), 7.29-7.34 (1H, m), 4.42-4.63 (2H, m), 4.08-4.15 (1H, m), 3.94 (1H, dd, J=11.44, 4.12 Hz), 3.85 (1H, ddd, J=4.20, 2.44, 2.21 Hz).

Workup

customwas then brought to 130° C.
stirringstirred for an additional 2 h
temperatureAfter cooling to RT
washThe resulting solution was washed with saturated aqueous sodium bicarbonate (2×50 mL), brine (50 mL)
dry with materialdried over MgSO4
filtrationfiltered
concentrationconcentrated in vacuo
customPurification by flash chromatography (Silica, EtOAc/Hexanes)

Sources & evidence

ORD record: ord-f6fe69e33a1f41ffa0c000fa77fc4bcf
Source dataset: uspto-grants-2014_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08637525B2

Reaction notes

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