Synthesis
General procedure for the synthesis of 2-hydroxy-5-trifluoromethylbenzoic acid from 3-trifluoromethylbenzoic acid:
III. General method for Pd(II)-catalyzed tert-butyl-hydroxylation reaction 02:
To a 50 mL high-pressure reactor equipped with a magnetic stir bar was added Pd(OAc)2 (11.2 mg, 0.05 mmol) followed by 3-trifluoromethylbenzoic acid (0.5 mmol), benzoquinone (54.0 mg, 0.5 mmol), KOAc (98.0 mg, 1 mmol), and N,N-dimethylacetamide (1.5 mL).
The reaction vessel was filled with O2 (20 atm), then evacuated and filled again with O2 (5 atm, repeated twice).
The reaction mixture was stirred at 115 °C for 15 h and then cooled to room temperature.
After completion of the reaction, the crude product was purified according to the previous post-treatment of hydroxylation reaction under 1 atm O2 conditions.
References
[1] Journal of the American Chemical Society, 2009, vol. 131, # 41, p. 14654 - 14655
[2] Patent: WO2011/37929, 2011, A2. Location in patent: Page/Page column 14; 19-20
[3] Synlett, 2016, vol. 27, # 2, p. 277 - 281
