Triisopropyl borate → 1-cyclopentyl-5-fluoro-3-(methoxycarbonyl)-6-methyl-1H-indol-2-ylboronic acid

Participants

Reaction Steps

Into a solution of methyl 1-cyclopentyl-5-fluoro-6-methyl-1H-indole-3-carboxylate (2.64 g, 9.6 mmol) and triisopropylborate (4.0 mL, 17.28 mmol) in THF (40 mL) at −78° C. was added LDA (1.5 M, 8.3 mL, 12.48 mmol) dropwise. The mixture was stirred for 45 min, and then treated with ice water and extracted with dichloromethane. The organic layer was dried over sodium sulfate and evaporated to give 1-cyclopentyl-5-fluoro-3-(methoxycarbonyl)-6-methyl-1H-indol-2-ylboronic acid as a semi-solid (3.1 g, ˜50% pure), which was used in next step without further purification.

Provenance & Evidence