Sodium Hydroxide → 7-(1,1-Dimethylethyl)-2-(pentafluoroethyl)-2H-1-benzopyran-3-carboxylic acid

Participants

Reaction Steps

The ester from Step 3 (1.58 g 4.20 mmol) was dissolved in THF (3 mL) and ethanol (3 mL), treated with 2.5 N sodium hydroxide (2 mL, 5 mmol), and stirred at room temperature for 23.3 hours. The reaction mixture was concentrated in vacuo, acidified with 3 N HCl yielding a suspension. The solid was collected by filtration and was recrystallized from ethanol-water to yield a yellow solid (0.76 g, 52%): mp 171.0–173.5° C. 1H NMR (acetone-d6/300 MHz) 7.93 (s, 1H), 7.39 (d, 1H, J=8.1 Hz), 7.18 (dd, 1H, J=8.1 Hz 1.8 Hz), 7.02 (s, 1H), 6.01 (dd, 1H, J=23.1 Hz 3.2 Hz), 1.32 (s, 9 H). FABLRMS m/z 351 (M+H). EIHRMS m/z 350.0945 (M+, Calc'd 350.0941). Anal. Calc'd for C16H15F5O3: C, 54.86; H, 4.32. Found: C, 54.88; H, 4.32.

Provenance & Evidence