合成路线1

MK-0974 (I) can be prepared by condensation of 2-oxo-1-(4-piperidinyl)-2,3-dihydro-1H-imidazo[4,5-b]pyridine (II) with aminoazepinone (III) using either p-nitrophenyl chloroformate (1) or carbonyl diimidazole (CDI) (2-5) in the presence of Et3N. Treatment of (I) with potassium tert-butoxide in ethanol gives the corresponding potassium salt ethanolate (2-5). The intermediate imidazopyridine (II) can be prepared by two related methods. Reductive alkylation of 2,3-diaminopyridine (IV) with 1-Boc-4-piperidone (V) in the presence of NaBH(OAc)3 in CH2Cl2 gives the piperidinylamino pyridine (VI), which on treatment with CDI in CH3CN yields the pyridoimidazolone derivative (VII). Acidic Boc group cleavage in (VII) then provides the target intermediate (II) (1). In a related method, 3-amino-2-chloropyridine (VIII) is reductively alkylated with 1-(ethoxycarbonyl)-4-piperidone (IX) using either NaBH(OAc)3 or NaBH4 in the presence of trifluoroacetic acid to provide (X), which is converted to the N-carbamoyl derivative (XI) upon treatment with chlorosulfonyl isocyanate. Then, cyclization of (XI) by means of palladium diacetate and bis(diphenylphosphino)butane leads to the protected imidazopyridinone (XII), from which the N-carbethoxy group is removed by hydrolysis under alkaline conditions to furnish intermediate (II) (2-5). Scheme 1.