Experimental

In a flame dried round bottom flask molecule 18 (368 mg, 0.686 mmol) was dissolved in dichloromethane (DCM) (6.9 mL, 0.1 M) and cooled to -78°C. DIBAL was added dropwise (1M solution in hexanes, 2.4 mL, 2.4mmol, 3.5 eq) to the flask and stirred for 30 minutes at -78°C. Methanol (CH3OH) (0.25 mL) was used to quench the solution and the solution was warmed to room temperature. Ethyl acetate was added to dilute the solution. Hydrochloric acid (HCL) (3M, 15 mL) was added and the biphasic mixture was stirred vigorously for 15 minutes. The layers were separated and the aqueous layer was exhaustively extracted with ethyl acetate (4 x 5 mL). The organic layer was washed with brine (10 mL), dried with sodium sulfate (MgSO4), and concentrated to give the crude product. The crude product of Molecule 19 was obtained as an orange/red foam and carried onto the next step without purification, quickly in order to prevent decomposition. In order to purify Molecule 19, the crude product was dissolved in DCM and extracted exhaustively with 10% aqueous sodium hydroxide (NaOH). The combined base washes were then acidified and back extracted with ethyl acetate. The purified Molecule 19 (63% yield isolated on 35 mg scale) was obtained as a light yellow foam.

Purified Molecule 19 Product (63% yield isolated on 35 mg scale): Rf = 0.76 (silica gel, EtOAc); HRMS (m/z): calcd for C22H18O7, [M-H]-, 393.0980; found, 393.0976; IR (film) νmax: br 2923, 1702, 1503, 1490, 1250, 1035, 929 cm-1;1H NMR (400MHz, CDCl3): δ 9.85 (d, J = 1.9 Hz, 1 H), 6.91 (d, J = 1.6 Hz, 1 H), 6.81 – 6.72 (m, 5 H), 6.46 (dd, J = 15.7, 0.7 Hz, 1 H), 6.12 (dd, J = 15.8, 6.9 Hz, 1 H), 5.95 (d, J = 2.3 Hz, 4 H), 3.83 (t, J = 9.6 Hz, 1 H), 3.51 – 3.38 (m, 1 H), 3.23 – 3.04 (m, 2 H) ppm; 13C NMR(CDCl3, 101 MHz): δ 200.3, 178.3, 148.2, 148.1, 147.6, 146.9, 134.3, 131.6, 130.8, 126.7, 121.4, 119.9, 108.5, 108.4, 107.3, 105.7, 101.3, 101.2, 55.6, 48.3, 40.7, 39.7 ppm.