Trimethyl borate → 1H-Indole-1-carboxylic acid, 2-borono-5-[[4-[(1,1-dimethylethoxy)carbonyl]-1-piperazinyl]sulfonyl]-, 1-(1,1-dimethylethyl) ester (9CI)

Participants

Reaction Conditions

Reaction Steps

A solution of the tert-butyl 5-{[4-(tert-butoxycarbonyl)piperazin-1-yl]sulfonyl}-1H-indole-1-carboxylate (2-4, 1.06 g) in THF (55 mL) was stirred at −78° C. and treated with t-BuLi (1.7M, 2.68 mL, 4.55 mmol). After stirring for 45 minutes, the solution was treated with trimethylborate (640 μL, 5.69 mmol). The solution was warmed to 0° C. and stirred for 10 min, then partitioned between ethyl acetate (2×100 mL) and saturated NH4Cl solution (100 mL). The combined organics were dried over Na2SO4, filtered and concentrated to provide 1-(tert-butoxycarbonyl)-5-{[4-(tert-butoxycarbonyl)piperazin-1-yl]sulfonyl}-1H-indol-2-ylboronic acid (2-5) as a yellow foam. LRMS m/z: Cal'd for C22H32BN3O8S (M+H) 509.39, found 510.1.

Provenance & Evidence