[NH2:1][C:2]1[C:6]([C:7]([OH:9])=[O:8])=[CH:5][NH:4][N:3]=1.[CH:10]1([O:15][C:16]2[CH:17]=[C:18]([CH:21]=[CH:22][C:23]=2[O:24][CH3:25])[CH:19]=O)[CH2:14][CH2:13][CH2:12][CH2:11]1.C([BH3-])#N.[Na+]>CO>[CH:10]1([O:15][C:16]2[CH:17]=[C:18]([CH:21]=[CH:22][C:23]=2[O:24][CH3:25])[CH2:19][NH:1][C:2]2[C:6]([C:7]([OH:9])=[O:8])=[CH:5][NH:4][N:3]=2)[CH2:11][CH2:12][CH2:13][CH2:14]1To a suspension of 3-aminopyrazole-4-carboxylic acid (3.56 g, 0.023 mol) in 400 ml of methanol was added 3-cyclopentyloxy-4-methoxybenzaldehyde (5.06 g, 0.023 mole) and 95% sodium cyanoborohydride (1.85 g, 0.028 mol). The reaction mixture was stirred for 16 hours and then the methanol was evaporated under reduced pressure. The residue was treated with 100 ml of 15% aqueous NaOH and extracted twice with 100 ml portions of ether. The aqueous layer was acidified to pH 5 with 5N aqueous HCl and extracted twice with 100 ml portions of ethyl acetate. The ethyl acetate extracts were evaporated under reduced pressure and the residue was triturated with ether to give 3.7 g (49%) of the title compound, mp 134-136°, after recrystallization from methanol.
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