Cl[C:2]1[CH2:6][C:5]([CH3:8])([CH3:7])[CH2:4][C:3]=1/[CH:9]=[CH:10]/[C:11]([O:13][CH2:14][CH3:15])=[O:12].[N-:16]=[N+]=[N-].[Na+].O.C(Cl)Cl>CS(C)=O>[CH3:7][C:5]1([CH3:8])[CH2:6][C:2]2[NH:16][C:10]([C:11]([O:13][CH2:14][CH3:15])=[O:12])=[CH:9][C:3]=2[CH2:4]1A 250-mL single neck round bottomed flask equipped with a magnetic stirrer and nitrogen inlet was charged with 110a (17 g, 74 mmol) in DMSO (100 mL). To the solution was added sodium azide (9.6 g, 150 mmol). The mixture was then heated to 75° C. and stirred for 8 h. After cooling to rt, H2O (100 mL) and CH2Cl2 (200 mL) were added and the organic layer was separated. The aqueous layer was extracted with CH2Cl2 (50 mL). The combined organic layers were washed with brine, dried over sodium sulfate and concentrated in vacuo. The residue was purified by column chromatography using a 100% hexane-1:1 hexane/ethyl acetate gradient to afford a 37% yield (5.7 g) of 110b.
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