Potassium Carbonate → 5-(1-methyl-1H-pyrazol-5-yl)-3-thiophenecarboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-bromo-3-thiophenecarboxylic acid (875 mg, 4.23 mmol) in dioxane/H2O (5:1, 21 mL) was added K2CO3 (205 mg, 14.8 mmol), tetrakistriphenylphosphine Pd(0) (297 mg, 0.26 mmol) and 1-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (988 mg, 4.75 mmol). The reaction mixture was heated to 80° C. in a sealed tube. After 5 h, additional tetrakistriphenylphosphine Pd(0) (108 mg, 0.1 mmol) and 5-(5,5-dimethyl-1,3,2-dioxaborinan-2-yl)-1-methyl-1H-pyrazole (989 mg, 4.75 mmol) were added. After 12 h, the reaction solution was then partitioned between H2O—CHCl3, and the aqueous phase was washed several times with CHCl3. The aqueous phase was then adjusted to pH 3 with 2.5M HCl and the aqueous phase extracted with CHCl3. The combined organics were dried (Na2SO4), concentrated under vacuum and dried under high vacuum overnight and used without further purification: LC-MS (ES) m/z=209 (M+H)+.

Provenance & Evidence