Reaction Steps
A solution of alcohol 21 (530 mg, 1.54 mmol) in CH2Cl2 (5 mL) was treated with (2S)-1-(1,2-dioxo-3,3-dimethylpentyl)-2-piperidinecarboxylic acid (23, 393 mg, 1.54 mmol, followed by 1,3-dicyclohexylcarbodiimide (381 mg, 1.85 mmol), and 4-(dimethylamino)-pyridine (132 mg, 1.08 mmol) under a nitrogen atmosphere. The resulting bright yellow suspension was allowed to stir overnight. The mixture was then filtered through glass wool and chromatographed (silica gel, 20-60% EtOAc/hexanes) to give (1R)-3-(3-Pyridyl)-1-[3-(tert-butoxycarbonylmethoxy)phenyl]-1-propyl (2S)-1-(3,3-dimethyl-1,2-dioxopentyl)-2-piperidinecarboxylate (860 mg, 96%) as a colorless oil: 1H NMR (CDCl3, 300 MHz) (single diastereomer, mixture of rotamers) 8.46 (m, 2H), 7.50-6.80 (m, 6H), 5.80 (t, J=6.1 Hz, 1H), 5.32 (d, J=5.0 Hz, 1H), 4.54 (s, 2H), 3.38 (d, J=12.8 Hz, 1H), 3.14 (td, J=12.6, 3.0 Hz, 1H) 2.60 (m, 2H), 2.36 (d, J=13.7 Hz, 1H), 2.25 (m, 1H), 2.10 (m, 1H), 1.75 (m, 4H), 1.49 (s, 9H), 1.45 (m, 2H), 1.24 (s, 3H), 1.22 (s, 3H), 0.90 (t, J=7.4 Hz, 3H); 13C NMR (CDCl3, 75MHz) (single diastereomer, mixture of rotamers) 208.2, 175.1, 170.0, 168.2, 167.7, 158.6, 150.2, 148.1, 141.3, 136.6, 130.2, 123.8, 120.1, 115.0, 113.6, 107.9, 82.8, 66.1, 51.7, 47.1, 44.6, 39.2, 37.8, 34.4, 33.0, 29.2, 28.4, 26.7, 25.3, 23.9, 23.5, 21.6, 21.4, 9.1.
