CC1(C)CCCC(C)(C)N1.[Li]CCCC.[CH3:16][Si:17]([CH3:30])([CH3:29])[CH2:18][CH2:19][O:20][CH2:21][N:22]1[CH:26]=[CH:25][N:24]=[C:23]1[C:27]#[N:28].Cl[C:32]([O:34][CH2:35][CH3:36])=[O:33]>C1COCC1>[CH2:35]([O:34][C:32]([C:26]1[N:22]([CH2:21][O:20][CH2:19][CH2:18][Si:17]([CH3:30])([CH3:29])[CH3:16])[C:23]([C:27]#[N:28])=[N:24][CH:25]=1)=[O:33])[CH3:36]
To a solution of 2,2,6,6-tetramethyl-piperidine (0.365 mL, 2.17 mmol) in 4 mL of THF at −50° C. was added n-BuLi (1.08 mL, 2.17 mmol, 2M in pentane) and the mixture allowed to stir for 10 min at 0° C. The mixture was cooled to −50° C. and a solution of 1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole-2-carbonitrile (prepared in the previous step) (0.440 g, 1.97 mmol) in 2 mL of THF was added and the reaction stirred for 1 h at −50° C. and then ethyl chloroformate (0.210 mL, 2.17 mmol) was added. After 10 min at −50° C. the reaction was quenched with brine (20 mL) and extracted with EtOAc (2×20 mL) and the organic layer dried (Na2SO4) and concentrated. The title compound was eluted from a 20-g SPE column with 20% EtOAc/hexanes to give 0.280 g (48%) of a colorless oil. 1H-NMR (CDCl3, 400 MHz): δ 7.81 (s, 1H), 5.89 (s, 2H), 4.40 (q, J=7.1 Hz, 2H), 3.65 (m, 2H), 1.41 (t, J=7.1 Hz, 3H), 0.96 (m, 2H), 0.00 (s, 9H). Mass spectrum (ESI, m/z): Calcd. for C13H21N3O3Si, 296.1 (M+H), found 295.5.
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