A flame-dried, 250 mL round bottom flask was charged, under argon, with 4 (8 g, 23.6 mmol) and this was suspended in 35 mL of anhydrous ethanol. The flask was protected from light and then placed in an ice bath. Sodium borohydride (2.06 g, 54.3 mmol) was added in small portions and the reaction was allowed to stir at 0° C. for 180 minutes. At this time, saturated ammonium chloride (30 mL) was added slowly to the reaction mixture over a period of 20 minutes to minimize the gas evolution. Ethanol was evaporated in vacuo and the mixture was diluted with water (100 ml) and extracted with dichloromethane (3×100 mL). The combined organic layers were dried with magnesium sulfate, filtered, and the solvent was evaporated in vacuo to give orange oil. This oil was subjected to column chromatography (SiO2, 75×200 mm, 1% triethylamine in dichloromethane) to give, following solvent evaporation, 7.25 g (90%) of 5 as a yellow solid. Rf=0.30 (33% ethyl acetate/hexane). Mp >220° C. 1H NMR (400 MHz, DMSO-d6): δ7.67 (s, 1), 7.38 (s, 1), 5.55 (t, J=6.4 Hz, 1), 4.81 (d, J=6.4 Hz, 2), 4.04 (t, J=7.2 Hz, 2), 4.00 (t, J=7.6 Hz, 2), 3.91 (s, 3), 1.99 (s, 3), 1.76-1.72 (m, 2), 1.61-1.57 (m, 2), 1.45-1.37 (m, 4) ppm.
