[N+:1]([CH3:4])([O-:3])=[O:2].C1CCN2C(=NCCC2)CC1.CS(C)=O.[CH2:20]([O:22][C:23](=[O:30])[CH:24]=[CH:25][CH2:26][CH:27]([CH3:29])[CH3:28])[CH3:21]>C(Cl)Cl>[CH2:20]([O:22][C:23](=[O:30])[CH2:24][CH:25]([CH2:4][N+:1]([O-:3])=[O:2])[CH2:26][CH:27]([CH3:29])[CH3:28])[CH3:21]7.0 g of nitromethane and 3.3 mL of DBU (1,8-diazabicyclo[5.4.0]undece-7-en) were added to the DMSO solution of α,β-unsaturated ester VII. The reaction mixture was stirred until complete conversion was detected by GC. 20 mL of CH2Cl2 were added and the resulting mixture was washed with 2×20 mL of 1M aqueous H2SO4 and 1×20 mL of 0.5M aqueous NaHCO3. The organic layer was dried and the solvent was removed under reduced pressure. 3.6 g of γ-nitroester VIII were obtained (yield over two steps: 75%).
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