Hydrochloric Acid → (2E)-3-{4-[(3-fluoro-4-hydroxyphenyl)(2,2,6,6-tetramethyltetrahydro-4H-pyran-4-ylidene)methyl]phenyl}-2-propenoic acid

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Reaction Conditions

Reaction Steps

To a solution of ethyl (2E)-3-{4-[(3-fluoro-4-hydroxyphenyl)(2,2,6,6-tetramethyltetrahydro-4H-pyran-4-ylidene)methyl]phenyl}-2-propenoate (137) (0.30 g, 0.68 mmol) in a mixture of EtOH (6 mL) and THF (6 mL) was added an aqueous solution of 1 N NaOH (7 mL). The mixture was stirred at 60° C. for 2 h. Upon cooling, the mixture was acidified to pH=2 with an aqueous solution of 2 N HCl. The mixture was extracted with EtOAc (2×50 mL). The combined organic extract was washed with brine and dried over Na2SO4. Upon concentration and adding hexanes, the title compound 138 was obtained as an off-white solid (0.227 g, 81%). mp 125-128° C. 1H NMR (400 MHz, DMSO-d6): δ 1.10 (s, 6H), 1.12 (s, 6H), 2.10 (s, 2H), 2.14 (s, 2H), 6.47 (d, J=15.9 Hz, 1H), 6.75-6.80 (m, 1H), 6.82-6.95 (m, 2H), 7.19 (d, J=8.2 Hz, 2H), 7.54 (d, J=15.9 Hz, 1H), 7.61 (d, J=8.2 Hz, 2H), 9.80 (s, 1H), 12.36 (s, 1H). LCMS (ES): m/z 409 (M−H)−. Anal. Calcd for C25H27FO4.0.4H2O: C, 71.89; H, 6.71; Found: C, 71.88; H, 6.92.

Provenance & Evidence