C(=O)(OC(C)(C)C)[O:2][N:3]([CH2:9][CH2:10][C:11]([C:13]#[N:14])=[CH2:12])[C:4]([O:6][CH2:7][CH3:8])=[O:5].FC(F)(F)C(O)=O.C(=O)([O-])[O-].[K+].[K+]>ClCCl.CN(C)C=O>[C:13]([CH:11]1[CH2:12][O:2][N:3]([C:4]([O:6][CH2:7][CH3:8])=[O:5])[CH2:9][CH2:10]1)#[N:14]A solution of (3-cyano-3-butene-1-yl)(ethoxycarbonyl)azanyl 1,1-dimethylethyl carbonate (i.e. the product of Step G) and trifluoroacetic acid (3 mL) in dichloromethane (40 mL) was stirred at room temperature for 3 days. The reaction mixture was concentrated under reduced pressure to a tan oil. The oil was combined with potassium carbonate (3.6 g, 0.026 mol) in N,N-dimethylformamide (30 mL) and stirred at 80° C. for 24 h. The reaction mixture was concentrated under reduced pressure to near dryness. Methanol and dichloromethane were added and the precipitated solids were removed by filtration. The resulting solid was adsorbed onto Celite® (diatomaceous filter aid), and then purified by silica gel chromatography to provide the title compound as a pale-tan oil (0.645 g).
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