Sodium Hydroxide → 6-Methyl-2-(trifluoromethyl)-2H-1-benzothiopyran-3-carboxylic acid

Participants

Reaction Steps

The ester from Step 2 (0.55 g 1.8 mmol) was dissolved in THF (1.5 mL) and ethanol (1.5 mL), treated with 2.5 N sodium hydroxide (1.5 mL, 3.8 mmol), and stirred at room temperature for 88 hours. The reaction mixture was concentrated in vacuo, acidified with 3 N HCl, filtered, and recrystallized from diethyl ether/petroleum ether to yield the title compound as a yellow solid (0.14 g, 28%): mp 180.8–184.2° C. 1H NMR (acetone-d6/300 MHz) 7.95 (s, 1H), 7.42 (s, 1H), 7.31 (d, 1H, J=8.1 Hz), 7.25 (d, 1H, J=8.1 Hz), 4.94 (q, 1H, J=8.7 Hz), 2.34 (s, 3H). FABLRMS m/z 281 (M+Li). EIHRMS m/z 274.0250 (M+, Calc'd 274.0275). Anal. Calc'd for C12H9F3O2S: C, 52.55; H, 3.31. Found: C, 52.54; H, 3.35.

Provenance & Evidence