Tributylphosphine Oxide

• 4-(Dimethylamino)phenylboronic Acid (contains varying amounts of Anhydride) [D4428]
• Tributylphosphine Oxide [T0921]
• Methyl α-L-Fucopyranoside [M1051]
• N,N-Diisopropylethylamine (= DIPEA) [D1599]
• Acetonitrile

To a solution of methyl α-L-fucopyranoside (356 mg, 2 mmol), 4-(dimethylamino)phenylboronic acid (66 mg, 0.4 mmol, 0.2 equiv), tributylphosphine oxide (87 mg, 0.2 mmol, 0.2 equiv) and DIPEA (517 mg, 0.68 mL, 4.0 mmol, 2.0 equiv) in acetonitrile (10 mL) was added TBDPSCl (1.10 g, 1.03 mL, 4.0 mmol, 2.0 equiv) at rt and the mixture was stirred at 60 °C. After 24 h, methanol (1 mL) was added to the reaction mixture and the solvent was removed under reduced pressure. The residue was purified by column chromatography (ethyl acetate:hexane = 0:1 - 1:1 on silica gel) to give 1 as a colorless oil (510 mg，y. 61%).

The reaction mixture was monitored by TLC (ethyl acetate:hexane = 1:1, Rf = 0.59).

Compound 1

¹H NMR (400 MHz, CDCl₃); δ 7.75-7.67 (m, 4H), 7.48-7.36 (m, 6H), 4.68 (d, 1H, J = 3.2 Hz), 3.93-3.80 (m, 2H), 3.68 (brq, 1H, J = 6.5 Hz), 3.44-3.43 (m, 1H), 3.29 (s, 3H), 2.55 (brs, 1H), 1.53 (d, 1H, J = 8.9 Hz), 1.22 (d, 3H, J = 6.8 Hz), 1.10 (s, 9H).

• Regioselective silylation of pyranosides using a boronic acid / Lewis base co-catalyst system
• D. Lee, M. S. Taylor, Org. Biomol. Chem. 2013, 11, 5409.