Sodium hydride → 5-bromo-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-indazole-3-carbaldehyde

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Reaction Steps

To a suspension of NaH (6.6 g, 166 mmol, 1.10 eq) in DMF (500 mL) was added a solution of 5-bromo-1H-indazole-3-carbaldehyde (X) (34.0 g, 151 mmol, 1.00 eq) in DMF (50 mL) dropwise at 0° C. over a period of 30 min. The mixture was stirred at room temperature for 2 h, then SEM-Cl (26.4 g, 159 mmol, 1.08 eq) was added dropwise and the mixture was stirred at room temperature for another 3 h. Then the mixture was poured into an ice-water mixture (1000 mL) and extracted with EtOAc (300 mL×3), the organic phases were combined, dried over Na2SO4, filtered and concentrated in vacuo, the resultant residue was purified by flash chromatography on silica gel (PE:EtOAc=20:1→10:1) to afford 5-bromo-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-indazole-3-carbaldehyde (XIX) as a mixture of regioisomers (53.0 g, 151 mmol, 100% yield) as a yellow oil. ESIMS found for C1-4H19BrN2O2Si m/z 355 (M+H).

Provenance & Evidence