[C:1]([O:5][C:6](=[O:27])[CH2:7][C@@H:8]([CH2:15]OS(C1C=CC(C)=CC=1)(=O)=O)[CH2:9][C@H:10]([CH3:14])[CH2:11][CH2:12][CH3:13])([CH3:4])([CH3:3])[CH3:2].[N-:28]=[N+:29]=[N-:30].[Na+]>CS(C)=O.O>[C:1]([O:5][C:6](=[O:27])[CH2:7][C@@H:8]([CH2:15][N:28]=[N+:29]=[N-:30])[CH2:9][C@H:10]([CH3:14])[CH2:11][CH2:12][CH3:13])([CH3:4])([CH3:3])[CH3:2]Tosylate 104 (2.92 g, 7.3 mmol) and sodium azide (1.43 g, 0.02 mol) were warmed to ˜50° C. in DMSO (30 mL). After 2 hours the solution was cooled to room temperature and diluted with water. The solution was extracted with ether and the combined organic phases dried (MgSO4) and concentrated to give an oil 1.54 g, 79%. Further purification by flash chromatography (95% hexane/EtOAc) gave an oil. [α]D=−8.3 (c 1 in CHCl3). 13C NMR (100 MHz; CDCl3) 172.01, 80.73, 54.89, 39.73, 39.46, 39.00, 33.40, 29.85, 28.30, 20.15, 19.82, 14.52.
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