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

HRID 2370139Notes

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 (4 H, m), 7.29-7.34 (1 H, m), 4.42-4.63 (2 H, m), 4.08-4.15 (1 H, m), 3.94 (1 H, dd, J=11.44, 4.12 Hz), 3.85 (1 H, 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-bdce809963dd48f1915d179277b75f46
Source dataset: uspto-grants-2014_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08710061B2

Reaction notes

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