Triethylamine → HCID 58909332, compound

Participants

Reaction Steps

Trimethyl orthoacetate (0.94 mL, 7.4 mmol) is added to a suspension of compound 16 (2.9 g, 7.2 mmol) in 30 mL of CH2Cl2 stirred under nitrogen. Pyridinium p-toluenesulfonate (18 mg, 0.07 mmol) is added and the resulting pale yellow solution is stirred for 30 min and then concentrated to a white solid. This solid is dissolved in 30 mL of CH2Cl2, triethylamine (0.10 mL, 0.72 mmol) is added, and the mixture, under nitrogen, is cooled in an ice bath. Freshly distilled acetyl bromide (0.55 mL, 7.4 mmol) is added dropwise over 3-4 min with stirring. After 1 h, the ice bath is removed and aqueous 1 N NaHCO3 and CH2Cl2 are added. The aqueous phase is extracted with additional CH2Cl2 and the combined organic phases are dried over MgSO4 and concentrated to a white solid. This solid is suspended in 25 mL of methanol and 6 mL of THF, and cooled in an ice bath, under nitrogen. Pulverized KOH (0.60 g, 11 mmol) in 6 mL of methanol is added all at once. After 15 min the ice bath is removed and the mixture is allowed to come to ambient temperature over 70 min. The mixture is concentrated and taken up in ethyl acetate and aqueous 1N KH2PO4. The organic phase is washed with 1N NaHCO3 and then brine, dried over Na2SO4, and concentrated. Chromatography over silica gel, eluting with 20% ethyl acetate and 5% to 10% CH2Cl2 in heptane affords 2.0 g (5.2 mmol, 72%) of compound 17 as a white solid: 1H NMR (CDCl3) δ 7.45-7.30 (m, 5H), 6.99-6.86 (m, 3H), 5.12 (s, 2H), 4.43 (br, 1H), 3.63 (br, 1H), 2.90 (m, 2H), 2.79 (m, 2H), 2.74 (m, 1H), 1.39 (s, 9H); MS (CI) m/z 410.3 (MNa+), 388.3 (MH+).

Provenance & Evidence