Experimental
PhSeBr (538 mg, 2.28 mmol) was added to a stirred solution of 28 (311 mg, 0.457 mmol) and pyridine (0.920 mL, 11.42 mmol) in dichloromethane (46 mL) at -78 ̊C. The reaction was warmed to 0 ̊C after 10 minutes. The reaction mixture was then poured into aqueous
NaHCO3 after 1 h 20 min. The aqueous phase was extracted 3 times with dichloromethane. The combined organic layers were dried over
Na2SO4, filtered, and concentrated.
Silica gel chromatography (gradient 10% to 20% EtO Ac/hex) was used to yield 29 (320 mg, 92%) as a clear oil.
