An efficient synthesis for the preparation of N-[(3R,6S)-6-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)azepan-3-yl]-4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-1-yl)
piperidine-1-
carboxamide, by
coupling (3R,6S)-3-amino-6-(2,3-difluorophenyl)-1-(2,2,2-trifluoroethyl)azepan-2-one and 2-oxo-1-(4-piperidinyl)-2,3-dihydro-1H-imidazo[4,5-b]
pyridine dihydrochloride with 1,1′-
carbonyldiimidazole (“CDI”) as carbonyl source; an efficient preparation of the
potassium salt of N-[(3R,6S)-6-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)azepan-3-yl]-4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-1-yl)
piperidine-1-
carboxamide; efficient syntheses for the preparation of intermediates (3R,6S)-3-amino-6-(2,3-difluorophenyl)-1-(2,2,2-trifluoroethyl)azepan-2-one and 2-oxo-1-(4-piperidinyl)-2,3-dihydro-1H-imidazo[4,5-b]
pyridine dihydrochloride, and the
potassium salt of N-[(3R,6S)-6-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)azepan-3-yl]-4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-1-yl)
piperidine-1-
carboxamide including the
potassium salt ethanolate and potassium salt
hydrate.