Compound 4

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Compound data: 1H NMR

Compound data: 13C NMR

Compound data: COSY

Compound data: HSQC

Compound data: HMBC

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

To a 10 mL round-bottomed flask containing a solution of triol 28 (4.5 mg, 0.014 mmol) in ClCH₂CH₂Cl (0.15 mL) was added NaHCO₃ (17.0 mg, 0.203 mmol) and Dess–Martin periodinane (42.9 mg, 0.101 mmol) at 0 °C. The resulting mixture was heated to 60 °C. After 2 h, the reaction mixture was cooled to room temperature, and quenched by sequential addition of sat. Na₂S₂O₃ aq. (0.5 mL) and sat. NaHCO₃ aq. (0.5 mL). The resulting mixture was partitioned with EtOAc (5.0 mL) and H₂O (3.0 mL), and the phases were separated. The aqueous phase was extracted with EtOAc (5.0 mL × 3). The combined organic layers were washed with sat. NaHCO₃ aq. (3.0 mL), brine (3.0 mL), dried over MgSO₄, filtered, and concentrated to give a light yellow oil, which was used immediately in the next step without further purification. To a 10 mL round-bottomed flask containing a solution of the crude oil in CH₂Cl₂ (0.3 mL) and H₂O (0.03 mL) was added m-CPBA (4.7 mg, 0.027 mmol) followed by MnO₂ (11.7 mg, 0.135 mmol) at 0 °C. The resulting mixture was allowed to stir at 0 °C. After 2 h, MnO₂ was filtered off using a pad of Celite^® and the filter cake was rinsed with EtOAc (10 mL). The resulting filtrate was then sequentially washed with sat. Na₂S₂O₃ aq. (2.0 mL), sat. NaHCO₃ aq. (2.0 mL) and brine (2.0 mL), dried over MgSO₄, filtered and concentrated. The crude residue was purified by preparative thin-layer chromatography (90% EtOAc/ hexanes) to provide phomactin T (4) (1.5 mg, 31% over 2 steps). R_f: 0.20 (75% EtOAc/ hexanes); Optical Rotation: [α]²²_D = −39 (c 0.10, MeOH); ¹H NMR (700 MHz, CD₃OD at RT): δ 4.20 (br, 1H), 3.82 (s, 1H), 2.95 (br, 1H), 2.57 (br, 1H), 2.46 (br, 1H), 2.43–2.37 (m, 1H), 2.25 (br, 2H), 2.09–2.05 (m, 1H), 1.90–1.84 (m, 2H), 1.83–1.77 (m, 1H), 1.57–1.53 (m, 1H), 1.42 (s, 3H), 1.27 (s, 3H), 1.20 (s, 3H), 1.10 (d, J = 7.0 Hz, 3H); ¹H NMR (500 MHz, CD₃OD at 50 °C): δ 4.20 (d, J = 8.8 Hz, 1H), 3.83 (s, 1H), 2.85 (br d, J = 13.7 Hz, 1H), 2.55–2.39 (m, 3H), 2.30–2.18 (m, 2H), 2.13–2.06 (m, 1H), 1.92–1.78 (m, 3H), 1.59–1.54 (m, 1H) 1.43 (s, 3H), 1.27 (s, 3H), 1.22 (s, 3H), 1.10 (d, J = 7.0 Hz, 3H); ¹³C NMR (226 MHz, CD₃OD at 50 °C): δ 195.1, 170.0, 159.6 (assigned by HMBC), 136.2, 90.6, 64.7, 64.3, 43.5, 40.8, 39.4 (assigned by HMBC), 34.8 (assigned by HMBC), 33.0, 31.6, 30.2, 22.6, 22.5, 20.0, 16.7; HRMS (EI): Calc’d for C₂₀H₂₆O₆ [M]⁺: 362.1729, found: 362.1738