Ethanol → 5-Fluoro-3-(3-oxycyclopentyl)indole

Temperature

-20 °C

A mixture of 5-fluoroindole (6.0 g, 44.4 mmol) and 2-cyclopenten-1-one (4.5 mL, 53.3 mmol) in nitromethane (22 mL) was cooled to −20° C. in a carbon tetrachloride-dry ice bath. A mixture of boron trifluoride etherate (1.6 mL, 11.1 mmol) and ethanol (2.2 mL, 43 mmol) was added dropwise from an addition funnel. The reaction mixture was stirred at −20° C. for 2 hours, then was quenched with 5% aqueous sodium bicarbonate solution (100 mL), and extracted with ethyl acetate (3×200 mL). The combined organic layers were washed with water (100 mL) and brine (100 mL), then were dried over anhydrous sodium sulfate, filtered and concentrated to give 9.5 g of the title compound. Trituration with ethyl acetate afforded 5.6 g (58%) of the title compound as a yellow solid. An analytical sample was recrystallized from ethyl acetate/methanol: mp 119-120° C.; MS (ESI) m/z 218 [M+H]+.

1. additionwas added dropwise from an addition funnel
2. customwas quenched with 5% aqueous sodium bicarbonate solution (100 mL)
3. extractionextracted with ethyl acetate (3×200 mL)
4. washThe combined organic layers were washed with water (100 mL) and brine (100 mL)
5. dry with materialwere dried over anhydrous sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated

ORD record

ord-81b4ebeeecb540718c157456ac19b98e

Source dataset

uspto-grants-2005_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06911445B2