3-(1,3,2-Dioxaborinan-2-yl)pyridine → tert-butyl 4-{[4-amino-2-ethyl-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-1-yl]methyl}piperidine-1-carboxylate

Participants

Reaction Steps

tert-Butyl 4-[(4-amino-7-bromo-2-ethyl-1H-imidazo[4,5-c]quinolin-1-yl)methyl]piperidine-1-carboxylate (9.24 g, 18.9 mmol) and pyridine-3-boronic acid 1,3-propanediol cyclic ester (3.39 g, 20.8 mmol) were coupled according to the method described in Examples 118-121. Additional reagents were added after the reaction was heated for 16 hours, and the reaction was continued for 16 hours. Water (20 mL) was added, and the n-propanol was removed under reduced pressure. The remaining mixture was extracted with chloroform (2×200 mL), and the combined organic fractions were purified by column chromatography on silica gel (eluting with chloroform and chloroform:CMA). The resulting solid was recrystallized from acetonitrile to provide 5.44 g of tert-butyl 4-{[4-amino-2-ethyl-7-(pyridin-3-yl)-1H-imidazo[4,5-c]quinolin-1-yl]methyl}piperidine-1-carboxylate as a white, fluffy solid, mp 229-231° C.

Provenance & Evidence