Trimethyl borate → 8,8-Dimethyl-8H-10,12b-diazabenzo[a]aceanthrylene-3-boronic acid

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Reaction Steps

94 g (259 mmol) of 3-bromo-8,8-dimethyl-8H-10,12b-diazabenzo[a]aceanthrylene are dissolved in 1500 ml of dry THF, 135 ml (337 mmol) of a 2.5 M solution of n-butyllithium in cyclohexane are added dropwise at −70° C., after 1 h 37 ml of trimethyl borate (336 mmol) are added dropwise, the mixture is warmed to room temperature over the course of 1 h, the solvent is removed, and the residue, which is uniform according to 1H-NMR, is employed in the subsequent reaction without further purification. Yield: 59 g (181 mmol), 70% of theory, purity according to 1H-NMR about 96%.

Provenance & Evidence