Step 1:
tri(n-butyl)phosphine (1. 1 mL, 4.41 mmol) was added at 0 ºC to a mixture of alcohol 13(1.79 g, 2.98 mmol) and o-nitrophenyl selenocyanate (1.0 g, 4.40 mmol) in THF (3.0 mL). The deep wine red solution was stirred at 60 ºC for 3 h, and o-nitrophenyl selenocyanate (1.0 g, 4.40 mmol) was added as well as tri(n-butyl)phosphine (1.1 mL, 4.41 mmol). After being stirred for 3 h, the reaction mixture was cooled to room temperature and concentrated under reduced pressure. The mixture was passed through a short column of silica gel (hexane then EtOAc/hexane 1:32).3 The eluate was concentrated under reduced pressure.
Step 2:
In a solution of the intermediate and THF (15 mL), a 30% aqueous H2O2 solution (1.0 mL, 9.9 mmol) was added at 0 ºC. The yellow solution was turned into a bright red suspension within 10 min. After being stirred for 30 min, an aqueous Na2 S2O3 solution was added. The mixture was separated, and the aqueous layer was extracted with hexane. The combined organic layer was washed with brine, dried over MgSO4, and concentrated under reduced pressure. Purification by silica gel column chromatography (EtOAc/hexane 1:99) resulted in our product(1.52 g, 2.61 mmol, 88%) as a yellow oil.
