[C:1](=[O:6])(OC)[O:2][CH3:3].[CH3:7][N:8]1[CH2:12][CH2:11][CH2:10][CH:9]1[C:13]1[CH:18]([Si](C)(C)C)[CH:17]=[CH:16][N:15]([Si](C)(C)C)[CH:14]=1.CCCC[N+](CCCC)(CCCC)CCCC.[F-]>C1COCC1>[CH3:3][O:2][C:1]([N:15]1[CH:16]=[CH:17][CH2:18][C:13]([CH:9]2[CH2:10][CH2:11][CH2:12][N:8]2[CH3:7])=[CH:14]1)=[O:6]To a solution of dimethyl carbonate (0.05 mL, 0.6 mmol) in 2 mL of dry THF was slowly added 3-(1-methylpyrrolidin-2-yl)-1,4-bis-trimethylsilanyl-1,4-dihydropyridine I (0.2 mL, 0.68 mmol). A solution of TBAF in THF (0.06 mL, 0.06 mmol) was then introduced dropwise and the reaction mixture was stirred at RT for 1 h. The reaction was quenched with a saturated aqueous solution of NaHCO3. The aqueous layer was extracted with ether (2 times), and the combined organic layers were washed with brine and dried over K2CO3. The solvent was removed under reduced pressure and the crude material was purified by RPLC (hexanes) to afford 0.1374 g (91%) of 3-(1-methylpyrrolidin-2-yl)-4H-pyridine-1-carboxylic acid methyl ester II as a clear oil. IR (thin film, neat, NaCl): 2949, 2826, 2764, 1721, 1695, 1437, 1334, 1313, 1194, 983 cm−1. 1H NMR (300 MHz, CDCl3): δ 6.68–6.51 (m, 2 H), 4.88–4.77 (m, 1 H), 3.65 (s, 3 H), 2.95–2.91 (m, 1 H), 2.64–2.62 (m, 2 H), 2.41–2.33 (m, 1 H), 2.05–1.93 (m, 5 H), 1.68–1.53 (m, 4 H); 13C NMR (CDCl3, 75 MHz) δ 151.81, 123.15, 122.74, 120.28, 119.63, 118.08, 117.71, 106.22, 105.94, 70.37, 56.60, 53.05, 40.16, 40.08, 28.76, 28.38, 22.37, 21.56, 21.05. HRMS Calcd for C12H18N2O2: 223.1447 [M+H]+. Found: 223.1434 [M+H]+. [α]24D−65.5 (c=8, CH2Cl2).
Loading…
