Hydrochloric Acid → HCID 58233712, compound

Participants

Reaction Steps

Pyrrolidine (4.8 ml, 58 mmol) was added to a stirred solution of 1-(3-fluoro-2-hydroxyphenyl)ethanone (28) (5.9 g, 39 mmol) and tetrahydro-4h-pyran-4-one (4.6 ml, 50 mmol) in toluene (40 mL) at rt. After the exotherm subsided, the reaction mixture was stirred at rt for 1 h. then subjected to Dean-Stark reflux conditions for 6 h. The reaction mixture was cooled, poured into ice and 2 N HCl aqueous solution, and extracted with EtOAc (2×). The combined organics were washed with 2 N HCl aqueous solution (1×), 2 N NaOH aqueous solution (2×), brine (1×), and dried over Na2SO4. Concentration in vacuo gave 8-fluoro-2′,3′,5′,6′-tetrahydrospiro[chromene-2,4′-pyran]-4(3H)-one (29) (4.4 g, 48% yield) which was taken onto the next step without further purification. 1H NMR (400 MHz, DMSO-d6) δ ppm 7.51-7.60 (2H, m), 7.00-7.07 (1H, m), 3.60-3.73 (4H, m), 2.93 (2H, s), 1.71-1.92 (4H, m).

Provenance & Evidence