tert-Butyldiphenylchlorosilane

• 2,3-O-Isopropylidene-D-ribonic γ-Lactone [I1039]
• tert-Butyldiphenylchlorosilane (= TBDPSCl) [B1223]
• Imidazole [I0001]
• DMF

To a mixture of 2,3-O-Isopropylidene-D-ribonic γ-Lactone (13.2 g, 70.0 mmol) and imidazole (10.0 g, 147 mmol) in DMF (100 mL) at r.t. was added dropwise TBDPSCl (18.0 mL, 70.0 mmol). The reaction mixture was stirred at r.t. for 20 h, and then poured into ice water. The aqueous solution layer was extracted by diethyl ether. The organic layer was dried over Na₂SO₄ and concentrated under reduced pressure, and recrystallized from hexane to give 5-O-tert-butyldiphenylsilyl-2,3-O-isopropylidene-D-ribono-1,4-lactone (22.1 g, 74% yield) as a white solid.

The reaction mixture was monitored by TLC (hexane:ethyl acetate= 4:1, Rf = 0.5) and ¹H NMR.

¹H NMR (400 MHz, CDCl₃); δ 7.61-7.58 (m, 4H), 7.48-7.37 (m, 6H) , 4.88 (d, 1H, J = 5.2 Hz), 4.79 (d, 1H, J = 6.0 Hz), 4.56 (s, 1H), 3.89 (dd, 1H, J = 2.0, 11.2 Hz), 3.73 (d, 1H, J = 11.2 Hz), 1.47 (s, 3H), 1.38 (s, 3H), 1.02 (s, 9H).

• Chiral 1,4-dicarbonyl-2,3-O-isopropylidene derivatives. Rapid racemization on standing
• J. B. Rodriguez, Tetrahedron 1999, 55, 2157.