Potassium Phosphate, Tribasic → 4-(2-Fluoro-4-trimethylsilanylphenylamino)-indazole-1,5-dicarboxylic acid di-tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 2-fluoro-4-trimethylsilanyl-phenylamine (1.2 g, 6.5 mmol) in toluene (20 mL) was added to a mixture of 4-bromo-indazole-1,5-dicarboxylic acid di-tert-butyl ester (2.0 g, 5.0 mmol), Pd2 dba3 (114 mg, 2.5 mol %), Xantphos (144 mg, 5 mol %) and potassium phosphate tribasic (1.49 g, 7 mmol) under nitrogen. The atmosphere was evacuated and back-filled with nitrogen and then the reaction mixture heated at 90° C. for 18 hours. The cooled reaction mixture was diluted with ethyl acetate, filtered through Celite®, and the filtrate concentrated in vacuo. The resultant residue was subjected to flash chromatography (Si—PPC, dry loading on HM-N, gradient 0 to 10% ethyl acetate in cyclohexane) to give the title compound as an orange gum (1.9 g, 76%). 1H NMR (CDCl3, 400 MHz) 10.03 (1H, s), 8.05 (1H, d, J=9.03 Hz), 7.57 (1H, dd, J=9.00, 0.83 Hz), 7.28-7.18 (4H, m), 1.68 (9H, s), 1.63 (9H, s), 0.28 (9H, s).

Provenance & Evidence