To a stirred solution of 3-(1-methylpyrrolidin-2-yl)-1,4-bis-trimethylsilanyl-1,4-dihydropyridine i (0.2 mL, 1.36 mmol) in CH2Cl2 (6 mL) under Ar was added dropwise dimethylcarbamyl chloride (0.19 mL, 2.04 mmol). The reaction mixture was stirred at RT for 1 day. It was then poured into a saturated solution of NaHCO3 (3 mL). The aqueous phase was extracted with CH2Cl2 (5 times). The combined organic layers were washed with water and brine and dried over MgSO4. Evaporation of the solvent under reduced pressure afforded 0.49 g of crude material that was purified by RPLC (silica gel, 5% EtOAc/hex) to give 59% (0.2506 g) of 3-(1-methylpyrrolidin-2-yl)-4-trimethylsilanyl-4H-pyridine-1-carboxylic acid dimethylamide iii as a clear oil. IR (thin film, neat, NaCl): 3363, 2924, 2348, 1657, 1449, 1377 cm−1; 1H NMR (300 MHz, CDCl3) δ 6.65 (d, 1 H, J=6.9 Hz), 6.35 (s 1 H), 4.83–4.78 (m, 1 H), 3.14–3.09 (m, 1 H), 2.88 (s, 6 H), 2.80–1.25 (m, 13 H), 0.085 (s, 6 H); 13C NMR (100 MHz, CDCl3): δ 149.29, 147.15, 128.04, 124.49, 120.09, 106.29, 68.23, 57.35, 41.47, 38.53, 33.04, 30.34, 29.91, 22.37, 0.63, −2.00. HRMS Calcd for C16H29N3OSi: 308.2157 [M+H]+. Found: 308.2157 [M+H]+. [α]25D−15.17 (CH2Cl2, c=0.145).
