Sodium Carbonate → 3-Dipropylamino-8-fluoro-5-(2-furyl)chroman

Participants

Reaction Steps

In a three-necked round-bottom flask (25 mL) equipped with a magnetic stirrer and a reflux condensor the following reagents were mixed under nitrogen: 3-dipropylamino-8-fluoro-5-trifluoromethanesulfonylchroman (0.104 g; 0.25 mmol), absolute ethanol (1.7 mL), toluene (3.6 mL), 2-furylboronic acid (0.071 g; 0.64 mmol), lithium chloride (0.022 g; 0.51 mmol), 2M sodium carbonate (0.7 mL) and tetrakis(triphenylphosphine)palladium(0) (0.0073 g). The mixture was heated on an oil-bath to a reflux temperature (75°-80° C.). After 3 hours GC-analysis indicated a partial reaction (20% product and 66% starting material). Therefore more 2furylboronic acid (0.031 g; 0.28 mmol), absolute ethanol (0.2 mL) and tetrakis(triphenylphosphine)-palladium(0) (0.009 g) were added. The mixture was stirred at 75°-80° C. over night, then poured in 2M ammonia (40 mL) and extracted with ether (2×40 mL). The collected ether phases were dried (Na 2 SO4), filtered and concentrated in vacuo. The crude product was purified by flash-chromatography on a silica column with ethyl acetate/n-hexane (2:98). Relevant fractions were pooled and concentrated to give an oil consisting of impure product (72% GC). This material was purified in a second run by flash-chromatography on a silica column eluted with eluted with ethyl acetate/methylene chloride (1:99) to give 0.042 g (51% yield) of 3-dipropylamino-8-fluoro-5-(2-furyl)chroman as an oil.

Provenance & Evidence