[CH3:1][CH:2]([CH2:11][CH3:12])[CH2:3][CH:4]=[CH:5][C:6]([O:8][CH2:9][CH3:10])=[O:7].C1CCN2C(=NCCC2)CC1.[N+:24]([CH3:27])([O-:26])=[O:25]>C(#N)C>[CH3:1][CH:2]([CH2:11][CH3:12])[CH2:3][CH:4]([CH2:27][N+:24]([O-:26])=[O:25])[CH2:5][C:6]([O:8][CH2:9][CH3:10])=[O:7]Ethyl 5-methyl-2-heptanoate 12 (6.75 g, 39.70 mmol), DBU (6.0 g, 39.7 mmol), nitromethane (21.97 g, 359.9 mmol) in acetonitrile 80 mL was stirred at room temperature under nitrogen atmosphere overnight. The mixture was concentrated to an oil. A solution of the oil in ether was washed with 1N HCl, brine and dried. It was evaporated to give a light oil which was chromatographed on silica gel, eluting with 5% to 10% ether in Pet. ether to give 13 (3.6 g, 42%). 1H-NMR (CDCl3) δ4.49-4.39 (m), 4.12-4.07 (m), 3.61 (m), 2.36 (m), 1.36-1.18 (m), 0.86-0.79.
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