497 mg of alcohol 170 (1.73 mmol) was dissolved and 432 mg of ortho-nitrophenyl selenocyanate (1.90 mmol, 1.1 eq.) suspended in a solvent mixture consisting of 10 ml of anhydrous THF and 3 ml of anhydrous pyridine. This was followed by careful dropwise addition of 0.56 ml of tri-n-butylphosphine (2.25 mmol, 1.3 eq.) at 0° C. to obtain a dark-red solution. After one hour, the batch was diluted with 30 ml of MTBE, filtered over a small amount of silica gel and concentrated. The brown residue was purified using column chromatography over silica gel (EE/CH 1:3), thereby obtaining 685 mg of selenyl ether 171 (1.45 mmol, 84%) as an intensely yellow-colored oil.
