To a solution of N-t-butoxycarbonyl isonipecotic acid benzyl ester (13.34 g, 41.8 mmol) in THF (100 ml) at −78° C. was added sodium bis-trimethysilylamide (59 ml of a 1.0 M THF solution, 59 mmol) over 15 min. The resulting orange solution was stirred at −78° C. for 1 hr and then treated dropwise with 2-methyl benzyl bromide (6.80 ml, 50.7 mmol) and then allowed to warm slowly to room temperature over 16 hrs. The reaction was quenched with saturated aqueous NH4Cl, diluted with H2O, and extracted with EtOAc. The combined organic extracts were washed with brine, and concentrated in vacuo to an orange gum. Chromatography (SiO2, gradient elution, 20 to 30% EtOAc in hexanes) afforded the product as a white solid.
