4-(2-Methylquinolin-4-ylmethoxy)phenylamine as an HCl salt (94.0 mg, 0.28 mmol) and (6S,7S)-7-(tert-butoxycarbonyl)-5-azaspiro[2.5]octane-6-carboxylic acid (70.0 mg, 0.27 mmol) were dissolved in DMF (2.0 mL). BOP (143.0 mg, 0.32 mmol) was added to the above solution and then cooled to 0° C. Diisopropylethylamine (0.175 mL, 1.0 mmol) was added to the above mixture at 0° C. and then the reaction was stirred at room temperature for 2 h. The mixture was diluted with water, extracted with ethyl acetate, the combined extract was washed with brine, dried and concentrated. The crude tert-butyl(6S,7S)-6-[({4-[(2-methylquinolin-4-yl)methoxy]phenyl}amino)carbonyl]-5-azaspiro[2.5]octane-7-carboxylate (140 mg) was used in the next step without purification. ESI (M+H)+502.4.
