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

Participants

Reaction Steps

A solution of methyl 4-bromo-5-methyl-2-thiophenecarboxylate (2 g, 8.51 mmol)[prepared in Preparation 10], potassium carbonate (5.88 g, 42.5 mmol), 1-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (2.124 g, 10.21 mmol)[prepared according to Preparation 7] and bis(tri-t-butylphosphine)palladium(0) (0.217 g, 0.425 mmol) in 1,4-Dioxane (35.4 ml) and H2O (7.09 ml) was stirred at 80° C. in a sealed tube for 1 h. The reaction mixture was then partitioned between H2O-DCM and the aqueous phase was washed several times with DCM. The combined organic fractions were dried over Na2SO4, concentrated and purified via column chromatography (silica, 25% EtOAc in hexanes) affording methyl 5-methyl-4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate. This reaction was run in several batches (1 g, 3×2 g) which were combined for workup and purification affording the title compound (5.5 g, 78% combined yield) as a viscous yellow oil: LCMS (ES) m/e 236 (M+H)+.

Provenance & Evidence