Trifluoroacetic acid → rac-N-(2-Amino-4-fluoro-2-methylbutyl)-7-[(2,6-difluorobenzyl)oxy]-2,5-dimethylpyrazolo[1,5-a]pyridine-3-carboxamide

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Reaction Steps

200 mg (0.45 mmol, about 75% purity) of 7-[(2,6-difluorobenzyl)oxy]-5-methyl-2-propylpyrazolo[1,5-a]pyridine-3-carboxylic acid from Example 4A were initially charged together with 274 mg (0.72 mmol) of HATU and 0.42 ml (2.41 mmol) of N,N-diisopropylethylamine in 2.8 ml of DMF, and the mixture was stirred for 20 min. A solution of 330 mg (1.27 mmol assuming a purity of about 75%) of rac-4-fluoro-2-methylbutane-1,2-diamine dihydrochloride from Example 86A in 1.4 ml of DMF and 0.63 ml (3.61 mmol) of N,N-diisopropylethylamine was added to the first reaction mixture and the mixture was stirred at RT for 1 h. The reaction solution was admixed with acetonitrile, water and TFA and purified by means of preparative HPLC (RP18 column, eluent:acetonitrile/water gradient with addition of 0.1% TFA). The product fractions were combined and concentrated. Subsequently, the residue was taken up in dichloromethane and a little methanol, and washed twice with saturated aqueous sodium hydrogencarbonate solution. The aqueous phase was extracted twice with dichloromethane. The combined organic phases were dried over sodium sulphate, filtered, concentrated and lyophilized. 75 mg of the target compound were obtained (37% of theory, 98% purity).

Provenance & Evidence