Water → 5-(2-Hydroxyphenyl)-thiophene-2-carboxylic acid

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Reaction Steps

Tetrakis(triphenylphosphine)palladium(0) (133 mg, 0.12 mmol) is added to a solution of 5-bromothiophene-2-carboxylic acid (850 mg, 4.6 mmol) in degassed THF (10 mL). The resulting solution is stirred for 5 min and then 2-(4,4,5,5-tetramethyl)-1,3,2-dioxaborolan-2-yl) phenol (1 g, 4.6 mmol) is added followed by aqueous Na2CO3 (2M, 6.9 mL). The mixture is heated at reflux overnight. The reaction mixture is allowed to cool, poured into water (50 mL), and washed with ether (3×50 mL). The aqueous layer is acidified with concentrated HCl to pH<2. The resulting precipitate is collected by filtration, washed with water and dried in vacuo to yield 5-(2-hydroxyphenyl)-thiophene-2-carboxylic acid (761 mg, 83%). MS for C11H7O3S (ESI) (M−H)+ m/z 219.

Provenance & Evidence