A mixture of ethyl 2-(2-chloropyridin-4-yl)propanoate (51) (1.55 g, 7.25 mmol), tert-butylcarbamate (2.55 g, 21.76 mmol), Pd2 dba3 (0.166 g, 0.181 mmol), caesium carbonate (3.55 g, 10.88 mmol) and Xantphos (0.210 g, 0.363 mmol) in THF (10 mL) was purged with nitrogen and heated at 65° C. for 48 hr. The mixture was then cooled to RT, diluted with water and extracted with ether. The ether layer was washed with water and brine and then dried (MgSO4) and evaporated in vacuo. The residue was purified by flash column chromatography (SiO2, 100 g, 5-10% EtOAc in isohexane, gradient elution) to afford the title compound (52) (1.35 g, 61%): m/z 295 (M+H)+ (ES+).
