Реакция #538240

Уравнение реакции

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

Выход 61.8%

Растворители

EtOAc

Условия реакции

Обработка

1. 1
   Другоеwas then brought to 130° C.
2. 2
   workup.STIRRINGstirred for an additional 2 h
3. 3
   ТемператураAfter cooling to RT
4. 4
   ПромывкаThe resulting solution was washed with saturated aqueous sodium bicarbonate (2×50 mL), brine (50 mL)
5. 5
   Сушкаdried over MgSO4
6. 6
   Фильтрацияfiltered
7. 7
   Концентрированиеconcentrated in vacuo
8. 8
   ДругоеPurification by flash chromatography (Silica, EtOAc/Hexanes)

Методика

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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