Compound 28

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Compound data: 1H NMR

Compound data: 13C NMR

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

A 20 mL round-bottomed flask was charged with a solution of bis-epoxyalcohol 26 (80.0 mg, 0.251 mmol) in THF (2.5 mL). To this solution was added CsOAc (242 mg, 1.26 mmol), 18-crown-6 (333 mg, 1.26 mmol) followed by Me₄NBH(OAc)₃ (198 mg, 0.754 mmol). The resulting suspension was heated to 60 °C. After 2 h, the vessel was allowed to cool to room temperature, NaOMe (0.5 M solution in MeOH, 10 mL, 5.0 mmol) was added and the resulting mixture was allowed to stir at room temperature. After 2 h, the reaction mixture was quenched with sat. NH₄Cl aq. (5.0 mL) and the mixture was partitioned with EtOAc (10 mL) H₂O (5.0 mL), and the phases were separated. The aqueous phase was extracted with EtOAc (5.0 mL × 3). The combined organic layers were washed with brine (5.0 mL), dried over MgSO₄, filtered, and concentrated. The crude residue was purified by column chromatography (SiO₂, 50% EtOAc/ hexanes) to provide triol 28 (53.2 mg, 63%) as a white amorphous powder. R_f: 0.15 (50% EtOAc/ hexanes); Optical Rotation: [α]²²_D = −32 (c 0.55, CHCl₃); ¹H NMR (600 MHz, CDCl₃): δ 5.74 (s, 1H), 5.59 (br, 1H), 5.03 (br, 1H), 4.90 (d, J = 9.5 Hz, 1H), 4.44–4.41 (m, 1H), 4.17 (d, J = 13.0 Hz, 1H), 4.10 (d, J = 13.0 Hz, 1H), 3.56 (br, 1H), 2.74 (s, 1H), 1.94–1.76 (m, 7H), 1.69 (dt, J = 12.0, 1.9 Hz, 1H), 1.61 (s, 3H), 1.53–1.49 (m, 1H), 1.48 (s, 3H), 1.41–1.37 (m, 1H), 0.96 (s, 3H), 0.88 (d, J = 6.9 Hz, 3H); ¹³C NMR (151 MHz, CDCl₃): δ 143.6, 135.0, 134.4, 127.9, 70.6, 70.2, 63.6, 61.3, 58.3, 41.6, 35.7, 35.6, 35.4, 32.1, 29.7, 23.0, 21.3, 21.1, 16.1, 15.4; HRMS (ESI): Calc’d for C₂₀H₃₂O₄Na [M+Na]⁺: 359.2193, found: 359.2198.