Bromine → 3-bromo-5-methyl-4,5-dihydro-6H-cyclopenta[b]thiophen-6-one

A total of 129 g (0.85 mol) of 5-methyl-4,5-dihydro-6H-cyclopenta[b]thiophen-6-one in 130 ml of CHCl3 were added to a suspension of 250 g (1.89 mol) of AlCl3 (anhydrous powder) in 350 ml of CHCl3 at 0° C. over 0.5 h. The reaction mixture was stirred for 10 min at this temperature; then a solution of 46.7 ml of Br2 (0.91 mol) in 90 ml of CHCl3 was added dropwise for 1 h. The resulting mixture was stirred for 1 h at room temperature and, then, poured over 2000 cm3 of ice. The organic layer was separated. The aqueous layer was extracted with 4×200 ml of CH2Cl2. The combined organic fractions were washed with 1000 ml of the saturated aqueous Na2CO3, dried over K2CO3, passed through a short Silica Gel 60 column (40-63 μm, d 40 mm, l 50 mm), and evaporated to dryness. Fractional distillation gave white crystalline product, b.p. 128° C./0.8 mm Hg. Yield 185 g (94%).

1. stirringThe resulting mixture was stirred for 1 h at room temperature
2. customThe organic layer was separated
3. extractionThe aqueous layer was extracted with 4×200 ml of CH2Cl2
4. washThe combined organic fractions were washed with 1000 ml of the saturated aqueous Na2CO3
5. dry with materialdried over K2CO3
6. customevaporated to dryness
7. distillationFractional distillation
8. customgave white crystalline product, b.p. 128° C./0.8 mm Hg

ORD record

ord-0e977d9c87ed4de3a9ce3084be23ece1

Source dataset

uspto-grants-2012_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08173828B2