Hydrochloric Acid → 3,4,5,6-Tetrahydro-2H-[1,2']bipyridinyl-4-carboxylic acid N'-pentanoyl-hydrazide

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Reaction Steps

The carboxylic acid from Preparation 2 (1.5 g, 7.3 mmol) was suspended in dichloromethane (40 mL) containing N,N-dimethylformamide (2 drops) and oxalyl chloride (1.27 mL, 14 mmol) in dichloromethane (5 mL) was added dropwise. The mixture was stirred for 5 hours at room temperature and then evaporated under reduced pressure. The residue was suspended in hexane and evaporate (3×20 mL). The residue was dissolved in dichloromethane and cooled to 0° C. and pentanoic acid hydrazide (1.7 g, 14.6 mmol) was added. 1-Methyl-pyrrolidin-2one (1.6 mL, 14.6 mmol) in dichloromethane (10 mL) was added drop wise and the mixture was stirred at room temperature for 16 hours. The solvent was evaporated under reduced pressure and the residue was triturated with diethyl ether. The material obtained was dissolved in water and acidified to pH 2 by addition of 2N hydrochloric acid. The acidic solution was filtered and the filtrate was washed with ethyl acetate (3×20 mL) then basified with sodium carbonate. The solid formed was triturated with diethyl ether and isolated by filtration to give the title compound as a white solid (0.68 g).

Provenance & Evidence