Trimethyl borate → 1H-Indole-1-carboxylic acid, 2-borono-5-[(4-methyl-1-piperazinyl)sulfonyl]-, 1-(1,1-dimethylethyl) ester

Participants

Reaction Conditions

Reaction Steps

A solution of tert-butyllithium (1.7 M, 6.20 mL, 10.5 mmol, 2.00 equiv) in pentane was added to a solution of tert-butyl 5-[(4-methylpiperazin-1-yl) sulfonyl]-1H-indole-1-carboxylate (1-9, 2.00 g, 5.27 mmol, 1 equiv) in THF (150 mL) at −78° C. The resulting orange-colored reaction mixture was stirred at −78° C. for 1.5 hours before trimethyl borate (1.50 mL, 13.2 mmol, 2.50 equiv) was added. The mixture was warmed to 0° C. where it was stirred for 20 minutes, then partitioned between aqueous half-saturated ammonium chloride solution (200 mL) and EtOAc (2×200 mL). The organic layer was dried over sodium sulfate and concentrated to give 1-(tert-butoxycarbonyl)-5-[(4-methylpiperazin-1-yl)sulfonyl]-1H-indol-2-ylboronic acid (1-10) as a white solid. 1H NMR (300 MHz, CDCl3) δ 8.12 (d, 1H, J=8.8 Hz), 8.02 (d, 1H, J=1.6 Hz), 7.71 (d, 7.71 (dd, 1H, J=8.6, 1.8 Hz), 7.49 (s, 1H), 3.05 (br m, 4H), 2.48 (br m, 4H), 2.25 (s, 3H), 1.75 (s, 9H).

Provenance & Evidence