Triethylamine → 4-Nitrophenyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl carbonate

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Reaction Steps

4-(Hydroxymethyl)phenylboronic acid pinacol ester (0.5 g, 2.1 mmol) was dissolved in 20 mL of dry THF. Triethylamine (0.6 mL, 4.3 mmol) was added followed by 4-nitrophenyl chloroformate (0.47 g, 2.3 mmol) and the reaction was allowed to stir at room temperature for 1 h. The reaction was diluted with ethyl acetate and washed with 1.0 M HCl followed by saturated NaHCO3. The organic layer was dried over MgSO4, filtered and concentrated. Compound B21a was purified on a silica gel column eluting with 5% EtOAc in hexanes to give 0.51 g (1.3 mmol, 60% yield) as a white solid. 1H NMR (400 MHz, CDCl3) δ=8.25 (d, J=9.2 Hz, 2H), 7.85 (d, J=8.0 Hz, 2H), 7.43 (d, J=8.0 Hz, 2H), 7.36 (d, J=9.2 Hz, 2H), 5.31 (s, 2H), 1.35 (s, 12H). 13C NMR (100 MHz, CDCl3) δ=155.7, 152.7, 145.6, 137.2, 135.4, 127.9, 125.5, 122.0, 84.2, 71.0, 25.1. ESI-MS(+): m/z 417.19 [M+NH4]+, 422.20 [M+Na]+.

Provenance & Evidence