Hydrochloric Acid → HCID 21883633, compound

Participants

Reaction Steps

Preparation of 2-trifluoromethyl-3H-naphthopyran-carboxylic acid. A solution of the ester from Step 1 (0.8 g, 2.5 mmol) was dissolved in 40 mL of ethanol and 10 mL of tetrahydrofuran, treated with sodium hydroxide (2.5 N, 10 mL, 25 mmol) and stirred at room temperature for 16 hours. The reaction mixture was acidified with 1.0 N HCl, whereupon a solid formed that was isolated by filtration. The solid was washed with 20 mL of water to afford 0.7 g (95%) of the title compound as a yellow solid: mp 245.9–248.6° C. 1H NMR (acetone-d6/300 MHz) 8.57 (s, 1H), 8.28 (d, 1H, J=8.7 Hz), 8.03 (d, 1H, J=9.0 Hz), 7.93 (d, 1H, J=8.7), 7.67 (m, 1H), 7.50 (m, 1H), 7.28 (d, 1H, J=9.0), 5.96 (qH-F, 1H, J=7.2 Hz). FABHRMS m/z 295.0561 (M+H, Calc'd 295.0582). Anal. Calc'd for C15H9O3F3+3.31% H2O: C, 59.21; H, 3.35. Found: C, 59.17; H, 3.07.

Provenance & Evidence