Boron tribromide → HCID 21957872, compound

HRID 918793Notes

Reaction equation

C[O:2][C:3]1[CH:4]=[C:5]2[C:10](=[CH:11][CH:12]=1)[S:9][C:8]([CH3:14])([CH3:13])[CH2:7][C:6]2=[O:15].B(Br)(Br)Br>C(Cl)Cl>[OH:2][C:3]1[CH:4]=[C:5]2[C:10](=[CH:11][CH:12]=1)[S:9][C:8]([CH3:13])([CH3:14])[CH2:7][C:6]2=[O:15]

Participants

Conditions

Temperature: -23 °C

Procedure

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).

Workup

temperaturewas cooled to −78° C.
customquenched by the slow addition of 50 mL of H2O
temperatureUpon warming to room temperature the aqueous layer
extractionwas extracted with CH2Cl2
washthe combined organic layers were washed with saturated aqueous NaHCO3, H2O, and saturated aqueous NaCl
dry with materialbefore being dried over MgSO4
customRemoval of the solvents under reduced pressure
customgave a green-brown solid which
customupon recrystallization (Et2O/hexanes)

Sources & evidence

ORD record: ord-c70f20b660964b578f82df14767e2fb9
Source dataset: uspto-grants-2016_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09271946B2

Reaction notes

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