Hydrochloric Acid → {1-[tert-Butyl(dimethyl)silyl]-5-fluoro-1H-indol-4-yl}boronic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 1-(tert-butyl-dimethyl-silanyl)-5-fluoro-1H-indole (30.0 g, 0.12 mol) in anhydrous THF (1000 mL) were added N,N,N′,N′-tetramethylethylenediamine (36.6 mL, 0.241 mol) and a solution of s-butyl lithium (1.4 M in cyclohexane, 172 mL, 0.241 mmol) at −78° C. The resulting mixture was stirred at −78° C. for 2 h, then triisopropyl borate (37.5 mL, 162.7 mmol) was added dropwise. The resulting solution was stirred at −78° C. for 40 min, then allowed to warm to −20° C. An aqueous solution of HCl (2.4 M, 250 mL) was added and the resulting mixture was poured into H2O. The layers were separated and the aqueous layer extracted with EtOAc. The combined organic layers were dried (MgSO4) and concentrated in vacuo. The resultant yellow solid was then crystallised from DCM and cyclohexane to give the title compound as a white solid (25.0 g, 71%).

Provenance & Evidence