Triisopropyl borate → HCID 71285344, compound

Participants

Reaction Steps

To a solution of tert-butyl 5-(4,6-bis(benzyloxy)-5-((benzyloxy)carbonyl)-3-ethylpyridin-2-yl)-1H-indole-1-carboxylate, prepared according to the protocol described in Example 412, step 3 (3.07 g, 4.59 mmol), triisopropylborate (1.17 mL, 5.51 mmol) in THF (15 mL), at −78° C. was added while stirring, LDA (3.67 mL, 1.5 M in cyclohexane, 5.51 mmol). The mixture was stirred for 0.5 h after the addition and the cooling bath was removed to allow the reaction mixture to warm to room temperature and stirred for an additional 0.5 h. The reaction was quenched with 6 N HCl at 0° C. and acidified to pH 4 and the mixture was diluted with DCM and water. The organic layer was separated, washed with water, brine and dried over anhydrous Na2SO4. The filtrate was concentrated and chromatographed (ethyl acetate in DCM, 0-40%) to give the boronic acid intermediate as light yellow powder (0.78 g) in 24% yield.

Provenance & Evidence