Reaktion #538240

Reaktionsgleichung

3-phenyldihydro-2H-pyran-4(3H)-one

carbonisocyanatidic chloride

→

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

Ausbeute 61.8%

Lösungsmittel

EtOAc

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigewas then brought to 130° C.
2. 2
   workup.STIRRINGstirred for an additional 2 h
3. 3
   TemperaturAfter cooling to RT
4. 4
   WaschenThe resulting solution was washed with saturated aqueous sodium bicarbonate (2×50 mL), brine (50 mL)
5. 5
   Trocknendried over MgSO4
6. 6
   Filtrationfiltered
7. 7
   Einengenconcentrated in vacuo
8. 8
   SonstigePurification by flash chromatography (Silica, EtOAc/Hexanes)

Vorschrift

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).

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