Potassium Carbonate → 4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylic Acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-bromo-2-thiophenecarboxylic acid (1 g, 4.83 mmol) in dioxane/H2O (5:1, 16 mL) was added K2CO3 (2.7 g, 19 mmol), tetrakistriphenylphosphine Pd(0) (279 mg, 0.241 mmol) and 5-(5,5-dimethyl-1,3,2-dioxaborinane-2-yl)-1-methyl-1H-pyrazole (1.2 g, 6.27 mmol). The reaction mixture was heated to 80° C. in a sealed tube for 2 h and additional tetrakistriphenylphosphine Pd(0) (279 mg, 0.241 mmol) and 5-(5,5-dimethyl-1,3,2-dioxaborinane-2-yl)-1-methyl-1H-pyrazole (1.2 g, 6.27 mmol) were added. After 12 h, the reaction was partitioned between 6N NaOH and DCM. The pH of the aqueous phase was adjusted to ˜3 with 3M HCl and washed several times with DCM. The combined organic fractions were dried (Na2SO4), concentrated under vacuum and used directly without further purification (˜1 g, quant.): LCMS (ES) m/z=209 (M+H)+.

Provenance & Evidence