Sulfuric Acid → HCID 71294430, compound

Participants

Reaction Steps

To prepare a starting compound of Formula III, 12 g of levulinic acid (0.104 mol, 1.0 eq) was first dissolved in 66 mL of water. A solution of 15.4 g of sodium carbonate (0.146 mol, 2.8 eq of base relative to levulinic acid) was slowly added. The resulting suspension was stirred for 30 minutes at room temperature. The reaction mixture was heated to 90° C., and a solution of 25 g of furfural (0.260 mol, 2.5 eq) in 25 mL of ethanol was added dropwise. The reaction mixture was stirred at 90° C. until complete, as determined by thin layer chromatography (TLC) (sys 9:1 CHCl3/HOAc). The reaction mixture was cooled to room temperature, and the pH was carefully adjusted to pH=2 with concentrated HCl. The solids were removed by filtration and dissolved in ethyl acetate twice (400 ml). The ethyl acetate was treated with activated carbon, filtered and washed with ethyl acetate. Hexanes were added to the filtrate. The resulting slurry was filtered and washed with hexanes to give 6-(furan-2-yl)-3-(furan-2-ylmethylene)-4-oxohex-5-enoic acid as a brown solid (11.7 g, 41.3%, HNMR). A solution of 2 mL of sulfuric acid in 2 mL of ethanol was added to 10 g of 6-(furan-2-yl)-3-(furan-2-ylmethylene)-4-oxohex-5-enoic acid (0.0367 mol, 1.0 eq) in 100 mL of ethanol. The mixture was heated to reflux and stirred until complete, as determined by TLC (sys: 100% EtOAc). The reaction mixture was cooled to room temperature and poured slowly into a saturated sodium bicarbonate solution. The product was extracted with ethyl acetate, washed with saturated brine, treated with activated carbon and dried with sodium sulfate. The filtrate was evaporated to dryness to give ethyl 6-(furan-2-yl)-3-(furan-2-ylmethylene)-4-oxohex-5-enoate as an oil (9.7 g, 88% yield, HNMR, carbon nuclear magnetic resonance (13CNMR)).

Provenance & Evidence