3-Bromothiophene → 3-Bromothiophene-2-sulfonyl chloride

Chlorosulfonic acid (20 ml, 300 mmol) was added to a solution of 3-bromothiophene (8.15 g, 50 mmol) in methylene chloride (50 ml) at −78° C. over a 20 min. period. After the completion of addition, the cold bath was removed and stirring continued at ambient temperature for 1 hr. The reaction mixture was carefully added, dropwise, to crushed ice (100 g). The mixture was extracted with methylene chloride (2×100 ml). The combined organic layers was dried over MgSO4 and evaporated. The crude product was purified by flash chromatography on silica gel using hexane as the eluent resulting in 3-bromothiophene-2-sulfonyl chloride (4 g, 30% yield) and 4-bromothiophene-2-sulfonyl chloride (200 mg,≦1%).

1. additionAfter the completion of addition
2. customthe cold bath was removed
3. additionThe reaction mixture was carefully added
4. customdropwise, to crushed ice (100 g)
5. extractionThe mixture was extracted with methylene chloride (2×100 ml)
6. dry with materialThe combined organic layers was dried over MgSO4
7. customevaporated
8. customThe crude product was purified by flash chromatography on silica gel

ORD record

ord-79a30087cd614848ace3bffeaebb08c3

Source dataset

uspto-grants-2001_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06331637B1