[C:1]([O:5][C:6](=[O:14])[NH:7][CH:8]1[CH2:13][CH2:12][CH:11]=[CH:10][CH2:9]1)([CH3:4])([CH3:3])[CH3:2].[H-].[Na+].[CH2:17](I)[CH3:18].C1CCCCC1.C(OCC)(=O)C>CS(C)=O>[C:1]([O:5][C:6](=[O:14])[N:7]([CH2:17][CH3:18])[CH:8]1[CH2:13][CH2:12][CH:11]=[CH:10][CH2:9]1)([CH3:4])([CH3:2])[CH3:3]
To a solution of cyclohex-3-enyl-carbamic acid tert-butyl ester (Kampferer, P.; Vasella, A. Helvetica Chimica Acta 2004, 87, 2764-2789) (4.34 g, 22 mmol) in 20 ml of DMSO was added sodium hydride (880 mg, 60% dispersion, 22 mmol) and after one hour of stirring ethyl iodide (1.78 ml, 22 mmol). After further stirring for 2 hours at room temperature the reaction mixture was concentrated under reduced pressure. The residue was diluted with water and brine and extracted three times with ethyl acetate. The organic layers were dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and after chromatography (silica, cyclohexane/ethyl acetate=12/1) the title compound (Rf=0.30, 2.88 g, 58% yield) was obtained as colorless solid.
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