2,2-Difluoro-2-(fluorosulfonyl)acetic acid → benzyl 6'-bromo-4-(difluoromethoxy)spiro[cyclohexane-1,2'-inden]-1'(3'H)-one

Participants

Reaction Conditions

Reaction Steps

In a 25 mL round bottom flask was placed 6′-bromo-4-hydroxyspiro[cyclohexane-1,2′-inden]-1′(3′H)-one (368 mg, 1.252 mmol) and it was azeotroped twice with acetonitrile (2 mL/each). CuI (24 mg, 0.126 mmol) was added followed by acetonitrile (2.5 mL). This solution was purged under a stream of N2 for 30 seconds. The solution was heated to 60° C. under a nitrogen atmosphere. After being 5 minutes at 60° C., FSO2CF2CO2H (136 mL, 1.316 mmol) was added dropwise. After 1 hour, the reaction was quenched with H2O (10 mL) and diluted with diethyl ether (10 mL). The phases were separated and the aqueous phase was back-extracted with diethyl ether (5 mL). The combined organic phases were dried over Na2SO4, filtered and concentrated under reduce pressure. The crude material was purified by flash chromatography (ISCO, 40 g SiO2 cartridge, ethyl acetate/hexanes as the eluents). The corresponding fractions were combined and concentrated under reduce pressure yielding benzyl 6′-bromo-4-(difluoromethoxy)spiro[cyclohexane-1,2′-inden]-1′(3′H)-one (137 mg, 0.398 mmol, 32% yield). M+H=344.9, 1H NMR (CDCl3, 400 MHz) δ 7.86 (d, J=1.2 Hz, 1H), 7.69 (dd, J=8.0, 1.6 Hz, 1H), 7.33 (d, J=8.4 Hz, 1H), 6.26 (t, J=75.2 Hz, 1H), 4.20 (m, 1H), 2.98 (s, 2H), 2.14 (m, 2H), 1.80 (m, 2H), 1.65-1.52 (m, 4H).

Provenance & Evidence