1,4-Dioxane → 7-Cyclohexyl-6-(3'-methoxy-biphenyl-4-yl)-pyrazolo[1,5-a]pyrimidine-3-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of 60 mg (0.126 mmol) of 7-cyclohexyl-6-(4-iodo-phenyl)-pyrazolo[1,5-a]pyrimidine-3-carboxylic acid ethyl ester, 29 mg (0.19 mmol, 1.5 equiv) of 3-methoxyphenylboronic acid, 5 mg (0.0063 mmol, 5 mol %) of Pd catalyst, and 80 mg (0.378 mmol, 3 equiv) of potassium phosphate was placed into a carousel tube. After a vacuum and argon cycle, 1,4-dioxane (3 mL) was added, and the resulting mixture was heated at 80° C. under argon for 14 h. Since analysis by LC-MS revealed unreacted starting material still present, 29 mg (0.19 mmol, 1.5 equiv) of 3-methoxyphenylboronic acid, 10 mg (0.012 mmol, 10 mol %) of Pd catalyst, and 80 mg (0.378 mmol, 3 equiv) of potassium phosphate was added and heating was continued for 24 h. The reaction mixture was then diluted with ethyl acetate, filtered through a small pad of Celite, dried over sodium sulfate and evaporated to give a brown residue (crude coupling product), which was chromatographed on silica gel (Biotage; gradient elution 2% to 5% ethyl acetate in dichloromethane) to afford 47 mg (82% yield) of desired 7-cyclohexyl-6-(3′-methoxy-biphenyl-4-yl)-pyrazolo[1,5-a]pyrimidine-3-carboxylic acid ethyl ester as indicated by 1H NMR; LC-MS—calcd for C28H29N3O3 [M++H]+: 456.22, found: 456.2.

Provenance & Evidence