Potassium Carbonate → ethyl 6-formyl-2-(trifluoromethyl)-2H-1-benzopyran-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

A 50 mL round bottom flask was charged with 5-formylsalicylaldehyde (3.21 g, 21.39 mmol), ethyl 4,4,4-trifluorocrotonate (3.50 mL, 3.96 g, 23.53 mmol), dimethylformamide (15 mL) and potassium carbonate (2.95 g, 21.39 mmol) and heated to 60° C. for 12 hours. Additional ethyl 4,4,4-trifluorocrotonate (3.50 mL, 3.96 g, 23.53 mmol) was added and the reaction heated for 16 hours at 75° C. After cooling to room temperature, the reaction was partitioned between H2O and diethyl ether. The organic phase was washed with saturated NaHCO3 solution, KHSO4 solution (0.25 M), brine, treated with decolorizing carbon (warmed gently). The resulting black suspension was dried over MgSO4, vacuum filtered through diatomaceous earth, and concentrated in vacuo yielding an orange crystalline mass. This material was recrystallized from hot hexanes yielding the ester (1.51 g, 24%) as orange crystals: mp 84.3–86.2° C. 1H NMR (acetone-d6/300 MHz) 9.96 (s, 1H), 8.06 (d, 1H, J=2 Hz), 8.02 (s, 1H), 7.99 (dd, 1H, J=8.5, 2.0 Hz), 7.24 (d, 1H, J=8.5 Hz), 5.99 (q, 1H, J=7.1 Hz), 4.43–4.25 (m, 2H), 1.34 (t, 3H, J=7.3 Hz). FABLRMS m/z 301 (M+H). EIHRMS m/z 300.0605 (M+, Calc'd 300.0609). Anal. Calc'd for C14H11F3O4: C, 56.01; H, 3.69. Found: C, 56.11; H, 3.73.

Provenance & Evidence