background and overview[1]
2-benzyloxyphenylboronic acid pinacol ester is an ester compound that can be used as a pharmaceutical synthesis intermediate. if 2-benzyloxyphenylboronic acid pinacol ester is inhaled, move the patient to fresh air; if skin contact occurs, remove contaminated clothing, rinse the skin thoroughly with soap and water, and seek medical attention if you feel unwell.
structure
preparation method[1]
the preparation of 2-benzyloxyphenylboronic acid pinacol ester is as follows:
step 1: dissolve dimethylamine (5 mmol, 1.0 equiv) in et2o (10 ml). meotf (6.5 mmol, 1.3 equiv) was added dropwise at 0 °c. after the addition is complete, the reaction mixture is stirred for a further 15-60 minutes at 0°c. the solution was concentrated and washed with et2o (2 x 20 ml). the resulting compound was dried under vacuum to give the salt 2-(benzyloxy)-n,n,n-trimethylaniline triflate (2g): a white solid (1.8g, 92%). 1hnmr (mhz, d6-dmso) δ7.80 (dd, j=8.5, 1.2hz, 1h), 7.59 (ddd, j=8.3, 7.6, 2.9hz, 3h), 7.53-7.37 (m, 4h), 7.18 (ddd, j=8.6, 7.5, 1.4hz, 1h), 5.38 (s, 2h), 3.64 (s, 9h); 13c{1h}nmr (101mhz, d6-dmso) δ150.6, 135.5, 133.5, 131.9 , 128.8, 128.6, 128.4, 121.9, 121.4, 115.8, 71.0, 55.1; hrmsm/z (esi) calculated value c16h20no (m-otf) + 242.1539, measured value 242.1541.
step 2: add 4-methoxy-n,n,n-trimethylaniline trifluoromethanesulfonate 1a (63.6mg, 0.2mmol), bis-(pinacol) to a 25ml schlenk tube ) diboron (127.0 mg, 0.5 mmol), ni(cod)2 (3.3 mg under argon, 6 mol%), icy·hcl (6.5 mg, 12 mol%), kotbu (44.9 mg, 200 mol%), toluene (0.5ml) and 2-ethoxyethanol (0.5ml). the resulting mixture was stirred at 50°c for 24 hours under ar, monitored by tlc. the solution was then cooled to room temperature and the solvent was removed directly under vacuum. the crude product 2-benzyloxyphenylboronic acid pinacol ester was purified by silica gel column chromatography (ethyl acetate/petroleum ether = 1:100): white solid (34.3 mg, 55%).
1hnmr (mhz, cdcl3) δ7.72 (dd, j=7.3, 1.7hz, 1h), 7.63 (d, j=7.3hz, 2h), 7.44-7.35 (m, 3h), 7.31 (d, j=7.2hz, 1h), 7.04-6.91 (m, 2h), 5.14 (s, 2h), 1.38 (s, 12h); 13c{1h}nmr (101mhz, cdcl3) δ163.2, 137.6, 136.7, 132.5 , 128.1, 127.3, 12 acrylic resin 6.7, 120.6, 112.0, 83.4, 69.9, 24.9; atr-ftir (cm-1) 297 inorganic pigment 7, 2925, 2888, 2853, 1598, 1443, 1355, 1320, 1141, 1072 , 861, 761, 744, 656; hrmsm/z (esi) calculated value c19h24bo3 (m+h) + 311.1813, measured value 311.1821.
main reference materials
[1] nickel-catalyzedborylationofaryl-andbenzyltrimethylammoniumsaltsviac-nbondcleavage