Trifluoroacetic acid → 4-[(4-Chlorophenyl)sulfonyl]-6-fluoro-3,4-dihydro-2H-1-benzopyran

Temperature

0 °C

6-Fluorochroman-4-one (352 mg, 2.12 mmol) and 4-chlorothiophenol (320 mg, 2.2 mmol) were dissolved in 5 mL DCM. The reaction mixture was cooled to 0° C. and 2.4 mL of trifluoroacetic acid was added. After 5 min at 0° C., pyridine-borane complex (0.20 mL) was slowly added. The reaction mixture was stirred for 1 h at 0° C. Et2O (100 mL) and sat. NaHCO3 solution (100 mL) were added. The ether layer was dried over Na2SO4 and concentrated. The residue was dissolved in 10 mL DCM, mCPBA (77%, 1.01 g, 4.50 mmol) was added and the reaction mixture was stirred at room temperature overnight. 2 g of Na2SO3 in 20 mL of water was added and the reaction was stirred for 1 h then filtered. The layers were separated, then the organic layer was washed with 1N NaOH solution (100 mL), dried over Na2SO4 and concentrated. The product was purified by column chromatography using hex./EtOAc as the eluent (gradient from 100/0 to 30/70 in 60 min, 0.37 g, 53%). 1H NMR (CDCl3 400 MHz) δ 7.67 (d, J=8.8 Hz, 2H), 7.49 (d, J=8.8 Hz, 2H), 6.92 (m, 2H), 6.77 (m, 1H), 4.24 (m, 2H), 4.10 (m, 1H), 2.36 (m, 1H), 2.18 (m, 1H).

1. additionpyridine-borane complex (0.20 mL) was slowly added
2. dry with materialThe ether layer was dried over Na2SO4
3. concentrationconcentrated
4. dissolutionThe residue was dissolved in 10 mL DCM
5. stirringthe reaction mixture was stirred at room temperature overnight
6. stirringthe reaction was stirred for 1 h
7. filtrationthen filtered
8. customThe layers were separated
9. washthe organic layer was washed with 1N NaOH solution (100 mL)
10. dry with materialdried over Na2SO4
11. concentrationconcentrated
12. customThe product was purified by column chromatography
13. customas the eluent (gradient from 100/0 to 30/70 in 60 min, 0.37 g, 53%)

ORD record

ord-995985fae22744a5a972c01d737591fd

Source dataset

uspto-grants-2011_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08067621B2