N-bromobutanimide → 848357-82-4

Temperature

50 °C

A mixture of 1-(thieno[3,2-c]pyrazol-1-yl)-ethanone (5.00 g, 30.1 mmol), N-bromosuccinimide (16.1 g, 90.4 mmol), and chloroform (100 mL) was heated at 50° C. under nitrogen for 5 hours. The orange mixture was stirred at room temperature for an additional 17 hours. The red-orange mixture was filtered, the insolubles washed twice with dichloromethane (60 mL). The filtrate was washed with 10% aqueous NaHSO3 (60 mL) and then twice with water (60 mL), then dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluting with 30% ethyl acetate/heptane to 50% ethyl acetate/heptane to give 1-(5-bromo-thieno[3,2-c]pyrazol-1-yl)-ethanone [6.21 g, 84%, Intermediate (51)] as an off-white solid. TLC Rf 0.50 (silica, 40% ethyl acetate/heptane). LC/MS: 244.93 (M+H), RT=3.10 minutes; 1H NMR [300 Mhz, (CD3)2SO]: δ 8.12 (s, 1H), 7.67 (s, 1H), 2.67 (s, 3H).

1. filtrationThe red-orange mixture was filtered
2. washthe insolubles washed twice with dichloromethane (60 mL)
3. washThe filtrate was washed with 10% aqueous NaHSO3 (60 mL)
4. dry with materialtwice with water (60 mL), then dried over magnesium sulfate
5. concentrationconcentrated under reduced pressure
6. customThe residue was purified by silica gel column chromatography
7. washeluting with 30% ethyl acetate/heptane to 50% ethyl acetate/heptane

ORD record

ord-a8aa43b640d44292b95468dfafb58643

Source dataset

uspto-grants-2011_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07928231B2