To a solution of methyl N-(diphenylmethylene)alaninate from Step A (9.78 g, 36.6 mmol) in 60 ml DMF at 0° C. was added a 1M solution of sodium bis(trimethylsilyl)amide in THF (45.72 ml, 45.72 mmol) over a 20 min period. After 30 min, a solution of 4-picolyl chloride hydrochloride (3.00 g, 18.29 mmol) in 40 ml DMF was added to the reaction via cannula over a 25 min period. The reaction was warmed to rt and stirred for 5 h. The reaction was quenched with saturated aqueous NH4Cl and extracted with EtOAc (3×). The combined organic layers were washed with 3M LiCl (2×) and brine, dried over Na2SO4, filtered, and concentrated in vacuo. Purification by silica gel chromatography (0-40% EtOAc/hexanes) afforded methyl 2-[(diphenylmethylene)amino]-2-methyl-3-pyridin-4-ylpropanoate as a white solid (5.28 g, 81%). LCMS [M+H]=359.2. 1H NMR (d4-MeOH) δ 8.51 (dd, J=4.5, 1.5 Hz, 2H), 7.56 (dd, J=8.4, 1.4 Hz, 2H), 7.40-7.37 (m, 4H), 7.34-7.30 (m, 2H), 7.26-7.23 (m, 2H), 7.10-7.07 (m, 2H), 3.33 (A of AB, d, J=13.0 Hz, 1H), 3.27 (s, 3H), 3.18 (B of AB, d, J=12.9 Hz, 1H), 1.32 (s, 3H).
