Reacción #1005975

Ecuación de reacción

6-methoxy-2,2-dimethyl-thiochroman-4-one

BBr3

→

6-hydroxy-2,2-dimethylthiochroman-4-one

Rendimiento 40.0%

Disolventes

CH2Cl2

CH2Cl2

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturawas cooled to −78° C.
2. 2
   Otroquenched by the slow addition of 50 mL of H2O
3. 3
   TemperaturaUpon warming to room temperature the aqueous layer
4. 4
   Extracciónwas extracted with CH2Cl2
5. 5
   Lavadothe combined organic layers were washed with saturated aqueous NaHCO3, H2O, and saturated aqueous NaCl
6. 6
   Secadobefore being dried over MgSO4
7. 7
   OtroRemoval of the solvents under reduced pressure
8. 8
   Otrogave a green-brown solid which
9. 9
   Otroupon recrystallization (Et2O/hexanes)

Procedimiento

To a solution of 6-methoxy-2,2-dimethyl-thiochroman-4-one (6.0 g, 27 mmol) in 50 mL CH2Cl2 cooled to −23° C. was added BBr3 (20.0 g, 80.0 mmol; 80.0 mL of a 1M solution in CH2Cl2) over a 20 minute period. After stirring for 5 hours at −23° C. the solution was cooled to −78° C. and quenched by the slow addition of 50 mL of H2O. Upon warming to room temperature the aqueous layer was extracted with CH2Cl2 and the combined organic layers were washed with saturated aqueous NaHCO3, H2O, and saturated aqueous NaCl before being dried over MgSO4. Removal of the solvents under reduced pressure gave a green-brown solid which upon recrystallization (Et2O/hexanes) afforded 2.25 g (40%) of 6-hydroxy-2,2-dimethylthiochroman-4-one as a light brown solid. 1H NMR (300 MHz, CDCl3) δ: 7.63 (1H, d, J=2.8 Hz), 7.15 (1H, d, J=8.5 Hz), 7.01 (1H, dd, J=2.8, 8.5 Hz), 2.87 (2H, s), 1.46 (6H, s).

Fuente