A solution of alcohol 53 (1.26 g, 5.16 mmol) and triethylamine (1.43 ml, 10.32 mmol) in 80 ml of DCM is cooled to −78 C. Triflic anhydride (0.85 ml, 5.16 mmol) is slowly added and stirring continued for 1 hour. The mixture is then allowed to warm up to 0 C and cooled back to −78 C after 15 minutes. A solution of piperidin-4-yl-carbamic acid tert-butyl ester, 3, (1.03 g, 5.16 mmol) in 40 ml of DCM is slowly added at −78 C. After complete addition, the cooling bath is removed and the dark solution is allowed to warm up to room temperature. The mixture is washed twice with water, dried over sodium sulphate, filtered and evaporated. The crude is purified by chromatography on silicagel using DCM (saturated with ammonia) and MeOH (1%).
