Water → 2-Tolylboronic acid pinacol ester

Participants

Reaction Steps

To 200 ml (0.21 mol) of 1.07 M solution of 2-methyl phenylmagnesiumbromide in THF, 49.3 g (0.27 mmol) of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was added at room temperature. The resulting solution was stirred for 15 min at the same temperature, and then 50 ml of water was added. The formed mixture was poured into 500 ml of water, and crude product was extracted with 3×200 ml of ethyl acetate. The combined organic extract was dried over Na2SO4 and then evaporated to dryness. Fractional distillation of the residue in vacuum gave colorless oil, b.p. 81-84° C./3 mmm Hg. Yield 33.1 g (57%). Anal. calc. for C13H19BO2: C, 71.59; H, 8.78. Found: C, 71.78; H, 8.65. 1H NMR (CDCl3): 7.78 (m, 1H, 6-H), 7.33 (m, 1H, 5-H), 7.16-7.19 (m, 2H, 3, 4-H), 2.56 (s, 3H, Me in 2-MeC6H4), 1.36 (s, 12H, Bpin).

Provenance & Evidence