1H-Pyrazole-4-carboxamide,5-amino-1-cyclopentyl-(9CI) synthesis

Yield:666235-33-2 99%

Reaction Conditions:

Stage #1: 5-amino-1-cyclopentyl-1H-pyrazole-4-carbonitrilewith sulfuric acid at 20; for 2 h;
Stage #2: with ammonia in water;

Steps:

Compound 16; 5-Amino-1-cyclopentyl-1H-pyrazole-4-carboxylic acid amide; Compound 3 (3.34 g, 19.0 mmol) was treated with concentrated sulfuric acid (6 mL) as for the preparation of 12 above. The product was isolated via neutralization with concentrated ammonium hydroxide (80 mL), washing with water, and drying in vacuo as described for 12. 3.64 g (99%) of a fluffy white powder, Compound 16, was obtained. Compound 16: MS (ES⁺calculated: 194.24; found: 195.10 M+H). HPLC (97%) purity, retention time 1.739 minutes-Method C); ¹H NMR (400 MHz, DMSO-d₆) δ 7.62 (s, 1H), 7.10 (br s, 1H), 6.60 (br s, 1H), 6.14 (br s, 2H), 4.52 (m, 1H), 1.97-1.67 (m, 6H), 1.63-1.50 (m, 2H).

References:

US2007/281949,2007,A1 Location in patent:Page/Page column 19