CS(O[CH2:6][C@@H:7]1[O:12][CH2:11][CH2:10][N:9]([C:13]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14])[CH2:8]1)(=O)=O.[I-].[Na+].C(=O)([O-])[O-].[K+].[K+].[CH2:28]([O:35][C:36]([N:38]1[CH2:43][CH2:42][NH:41][CH2:40][CH2:39]1)=[O:37])[C:29]1[CH:34]=[CH:33][CH:32]=[CH:31][CH:30]=1>C(#N)CCC.CCCC(C)C.C(OCC)(=O)C.O>[CH2:28]([O:35][C:36]([N:38]1[CH2:43][CH2:42][N:41]([CH2:6][C@@H:7]2[O:12][CH2:11][CH2:10][N:9]([C:13]([O:15][C:16]([CH3:17])([CH3:18])[CH3:19])=[O:14])[CH2:8]2)[CH2:40][CH2:39]1)=[O:37])[C:29]1[CH:34]=[CH:33][CH:32]=[CH:31][CH:30]=1tert-Butyl (2R)-2-{[(methylsulfonyl)oxy]methyl}morpholine-4-carboxylate (75 g, 0.25 mol), sodium iodide (11.4 g, 76 mmol), potassium carbonate (38 g, 0.28 mol) and benzyl-1-piperazine carboxylate (54 mL, 0.28 mol) were heated together in butyronitrile (1.5 L) at 115° C. for 24 hours. Water (1.8 L) was added and the layers separated, the aqueous phase was washed with ethyl acetate (1 L) and the combined organics were washed with brine (1 L), dried (MgSO4) and evaporated to give crude product as a yellow oil. Chromatography (5 kg column: 20% ethyl acetate to 50% ethyl acetate in isohexane) gave product as pale yellow gum (73 g, 0.17 mol, 70%).
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