[Synthesis]
3.4. Synthesis of 4-methyl-1-naphthalenylboronic acid: Dissolve 1-bromo-4-methylnaphthalene (1.5 g, 6.78 mmol) in anhydrous ethyl ether (200 mL) and cool the solution to -78°C. Slowly add n-BuLi (1.7 M hexane solution, 10 mL), keeping the temperature at -78 °C. After addition, the reaction mixture was allowed to gradually warm to room temperature and stirred for 2 hours. The reaction mixture was again cooled to -78 °C and a solution of triisopropyl borate (4 g, 4.91 mL, 21.27 mmol) in ether (20 mL) was quickly added. After stirring at -78 °C for 30 min, it was brought to room temperature and continued stirring for 15 hours. Upon completion of the reaction, 100 mL of 2M HCl was added and the milky white emulsion was observed to gradually become clear. The ether layer was separated and the aqueous layer was extracted with ether (3 x 100 mL). All ether extracts were combined, dried with MgSO4, and the solvent was removed by rotary evaporation. The residual solid was recrystallized with hot CH2Cl2 to give a white solid product. Yield: 95%.1H NMR (300 MHz, CD2Cl2): δ 9.33 (d, J = 9.3 Hz, 1H), 8.59 (d, J = 7.0 Hz, 1H), 8.16 (d, J = 9.5 Hz, 1H), 7.65 (dd, 2H), 7.54 (d, J = 7.6 Hz, 1H), 2.82 (s, 3H). 13C NMR (75 MHz, CD2Cl2): δ 140.3, 137.5, 132.8, 132.3, 128.6, 126.5, 126.3, 125.9, 125.7, 124.6, 19.5; MS (CI, CH4): m/z calcd for C11H11BO2: 186.1; found : 186.1 [M+]. Calcd for C11H11BO2-H2O: C, 64.75; H, 6.42. Found: C, 62.91; H, 5.64. |
[References]
[1] Tetrahedron, 2012, vol. 68, # 46, p. 9371 - 9375,5
[2] Tetrahedron,
[3] Patent: CN107814795, 2018, A. Location in patent: Paragraph 0028; 0030
[4] Patent: CN107973777, 2018, A. Location in patent: Paragraph 0042; 0045; 0046
[5] Patent: CN108129453, 2018, A. Location in patent: Paragraph 0041; 0042; 0045; 0046 |