合成路线1

Condensation of the chloro hydrazone (I) with dihydropyridones (IIa) and (IIb) by means of triethylamine in boiling toluene affords the pyrazolopyridines (IIIa) and (IIIb), respectively (1, 2). Reduction of the nitro derivative (IIIa) by catalytic hydrogenation over Pd/C provides aniline (IV), which is acylated with 5-bromovaleryl chloride (V) in the presence of K2CO3 in THF to furnish the bromoamide (VI). Subsequent cyclization of (VI) by means of potassium ethoxide in EtOH/THF gives the piperidone (VII) (1). Alternatively, the intermediate (VII) is obtained by condensation of the iodo compound (IIIb) with valerolactam (VIII) by means of K2CO3 and CuI in hot DMSO (2). Finally, conversion of ethyl ester (VII) to the title carboxamide is effected by heating with anhydrous ammonia in ethylene or propylene glycol in a sealed vessel, or with formamide in DMF in the presence of trifluoroacetic acid and trimethyl orthoformate (1, 2). In a further method, the pyrazolopyridinone derivative (IX) is condensed with 1-(4-iodophenyl)-2-piperidinone (X) employing K2CO3 and CuI in DMSO at 125 °C to give the adduct (XI), which is converted to the title amide via activation with tert-butyl chloroformate and triethylamine in ethyl acetate, followed by reaction with ammonium hydroxide (3). Scheme 1.