Triisopropyl borate → 1-(tert-butoxycarbonyl)-6-cyclopropyl-1H-indol-2-ylboronic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of tert-butyl 6-cyclopropyl-1H-indole-1-carboxylate (1.93 g, 7.51 mmol) and triisopropylborate (2.58 mL, 11.26 mmol) in THF was added LDA (1.5 M in cyclohexane, 7.0 mL, 10.5 mmol) at −78° C. The mixture was stirred at −78° C. for 30 min, quenched with ice water (60 mL) and stirred for 15 min without cooling. The mixture was extracted with ethyl acetate 1:1 in hexane (20 mL). The aqueous layer was acidified with aq. 2 N HCl to pH 5 and then extracted with CH2Cl2 (60 mL). The organic layer was dried over Na2SO4 and concentrated to give 1-(tert-butoxycarbonyl)-6-cyclopropyl-1H-indol-2-ylboronic acid as a solid (2.0 g, 88% yield) that was used in the next step without further purification.

Provenance & Evidence