General procedure for the synthesis of bis(2-methyl-2,4-pentanediol) borate from 2-methyl-2,4-pentanediol: 2-methyl-2,4-pentanediol (FW: 118.18; 22.0 g, 101.6 mmol) was dissolved in toluene (40 mL), and tetrakis(dimethylamino)diboron (FW: 197.926; 9.9 g, 50 mmol ). The reaction mixture was stirred at room temperature. the temperature was raised to 100 °C within 10 min and the release of dimethylamine started after about 5 min. The reaction temperature was maintained at 100 °C for 60 min, during which time the release of dimethylamine was complete at 30 min. At the end of the reaction, toluene was removed by distillation under reduced pressure to give a solid product (99.6% GC purity). The solid product was recrystallized from a solvent mixture of toluene and petroleum ether (boiling point 80°C-100°C) (1:9, v/v) to give a colorless solid bis(2-methyl-2,4-pentanediol) diboronate (MF: C12H24B2O4; FW: 253.94): the first batch of product was 8.83 g, the second batch of product was 3.69 g, with a combined yield of 12.52 g and a yield of 98.6%; GC purity was 99.6%. Melting point 99-101.6 °C. 1H NMR (200 MHz, CDCl3) δ: 1.21 (d, J = 7 Hz, 6H), 1.28 (s, 12H), 1.47 (dd, J = 12, 14 Hz, 2H), 1.70 (dd, J = 14, 3 Hz, 2H), 4.14 (dm, 2H) ppm. 13C NMR (50 MHz, CDCl3) δ: 23.1, 28.3, 31.2, 46.2, 64.1, 70.3 ppm.
