Dimethylformamide → 5-Bromo-4-methylthiophene-2-carbaldehyde

Temperature

-40 °C

To a solution of diethylamine (28 g, 0.383 mol) in anhydrous THF (400 mL) was added a solution of n-BuLi (2.5 M, 153 mL, 0.383 mol) in hexane. The solution was then stirred at −40° C. under nitrogen for 30 minutes, cooled to −78° C. and treated dropwise with a solution of 2-bromo-3-methylthiophene (45 g, 0.254 mol) in anhydrous THF (450 mL). The reaction solution was stirred at −78° C. for 30 minutes and treated with anhydrous DMF (100 mL). The mixture was allowed to warm to ambient temperature and was quenched with 1N aqueous hydrochloride solution (1L). The product was extracted with ethyl acetate (3×450 mL). The extracts were washed with water, brine and dried (MgSO4). After removal of solvent in vacuo, the title compound was obtained as a white solid (46 g, 88.3%). A sample of the product was crystallized from hexane: mp 63-65° C.; IR (KBr) 1654 cm−1. 1H-NMR (CDCl3) δ 9.75 (s, 1H), 7.45 (s, 1H), 2.26 (s, 3H); MS (EI) m/z 204/206 (M+). Anal. Calc. For C6H5BrOS: C, 35.14; H, 2.46. Found: C, 35.00; H, 2.44.

1. temperaturecooled to −78° C.
2. stirringThe reaction solution was stirred at −78° C. for 30 minutes
3. temperatureto warm to ambient temperature
4. customwas quenched with 1N aqueous hydrochloride solution (1L)
5. extractionThe product was extracted with ethyl acetate (3×450 mL)
6. washThe extracts were washed with water, brine
7. dry with materialdried (MgSO4)
8. customAfter removal of solvent in vacuo

ORD record

ord-4d283f6616224ac49fd9ba643f15d5d1

Source dataset

uspto-grants-2004_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06713478B2