4-pyrazolyl-benzene boronic ester synthesis

Yield:1312478-63-9 100%

Reaction Conditions:

with potassium acetate;(1,1'-bis(diphenylphosphino)ferrocene)palladium(II) dichloride in 1,4-dioxane at 100;Inert atmosphere;

Steps:

1.A

1-(4-bromophenyl)-1 H-pyrazole (0.34 g, 1.5 mmol), bis(pinacolato)diborane (0.53 g, 2.1 mmol) and potassium acetate (446mg,4.5mmol) were combined in a 4 dram vial in 10ml_ dioxane. The reaction mixture was bubbled with nitrogen for 10 minutes then Pd(dppf)CI₂ (1 10mg, 0.15mmol) was added. The reaction was heated at 100°C overnight. The reaction was diluted with 20ml_ of EtOAc and 20ml_ of 1 : 1 saturated sodium bicarbonate / water. The organic layer was isolated and the aqueous layer was back-extracted once with 10ml_ of EtOAc. The organic layers were combined, dried over solid magnesium sulfate, filtered and concentrated. The crude material was puified by eluting the material through a short pad of silica gel with EtOAc to provide a dark solid (0.42 g, 100 %). MS (LCMS) m/z 271.4 (M+1 ). ¹H NMR (400 MHz,CHLOROFORM-d) δ ppm 1.35 (s, 12 H) 6.46 (dd, J=2.54, 1.76 Hz, 1 H) 7.68 - 7.72 (m, 2 H) 7.72 (d, J=1.76 Hz, 1 H) 7.85 - 7.90 (m, 2 H) 7.96 (d, J=1.76 Hz, 1 H).

References:

WO2011/73845,2011,A1 Location in patent:Page/Page column 37