Tetrahydrofuran → 3-Bromo-5-(1-methylethyl)benzoyl chloride

Temperature

-78 °C

1,3-Dibromo-5-isopropyl-benzene (1.57 g, 5.65 mmoles) was dissolved into anhydrous THF (50 mL) under nitrogen, and was chilled to −78° C. To this stirring solution was slowly (over 10 min) added t-BuLi (3.6 mL, 6.1 mmoles, 1.7M solution in pentane). After the addition was complete the mixture was allowed to stir at −78° C. for an additional 30 min. After this period CO2 was bubbled through the stirring solution and the temperature was allowed to warm to ambient temperature. CO2 bubbling was continued for 3 hours and afterwards the reaction was allowed to stir for an additional 6 hours. After this period 1H HCl (10 mL) was added and the mix was evaporated in vacuo (-THF). The resulting aqueous mixture was extracted with DCM (3×20 mL) and the organic layer was dried over anhydrous Na2SO4. Evaporation in vacuo yielded the crude carboxylic acid as a white solid. The crude acid (1.22 g, ˜5.0 mmoles) was dissolved into C6H6 (20 mL) and to this was added freshly distilled thionyl chloride (0.5 mL, 6.9 mmoles). This mixture was heated to reflux and stirred at this temperature for 16 hours. After this period the reaction mix was evaporated in vacuo to yield crude 3-bromo-5-isopropyl-benzoyl chloride (1.0 g, 68%—2 steps) as a yellow liquid. 1H-NMR (CDCl3): δ 8.08 (t, J=1.8 Hz, 1H), 7.89-7.87 (m, 1H), 7.68-7.66 (m, 1H), 2.98 (m, J=6.8 Hz, 1H), 1.28 (d, J=6.8 Hz, 6H).

1. custom(over 10 min)
2. additionAfter the addition
3. customAfter this period CO2 was bubbled through the stirring solution
4. temperatureto warm to ambient temperature
5. waitCO2 bubbling was continued for 3 hours
6. stirringto stir for an additional 6 hours
7. additionAfter this period 1H HCl (10 mL) was added
8. customthe mix was evaporated in vacuo (-THF)
9. extractionThe resulting aqueous mixture was extracted with DCM (3×20 mL)
10. dry with materialthe organic layer was dried over anhydrous Na2SO4
11. customEvaporation in vacuo
12. customyielded the crude carboxylic acid as a white solid
13. temperatureThis mixture was heated
14. temperatureto reflux
15. stirringstirred at this temperature for 16 hours
16. additionAfter this period the reaction mix
17. customwas evaporated in vacuo

ORD record

ord-3a8dfe7357ea4235aa6f101bf9338609

Source dataset

uspto-grants-2011_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08013001B2