5-Methyl-2-nitro-4,5,6,7-tetrahydropyrazolo[1,5-A]pyrazine → 5-methyl-4H,5H,6H,7H-pyrazolo[1,5-a]pyrazin-2-amine

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Reaction Steps

A 500-mL Parr reactor bottle was purged with nitrogen and charged with 10% palladium on carbon (50% wet, 800 mg dry weight) and a solution of 128a (4.00 g, 2.20 mmol) in ethanol (160 mL). The bottle was attached to Parr hydrogenator, evacuated, charged with hydrogen gas to a pressure of 45 psi and shaken for 2 h. After this time, the hydrogen was evacuated, and nitrogen was charged into the bottle. CELITE® 521 (1.0 g) was added, and the mixture was filtered through a pad of CELITE® 521. The filter cake was washed with ethanol (2×75 mL), and the combined filtrates were concentrated to dryness under reduced pressure to afford a 99% yield of 128b (3.31 g) as an orange solid. 1H NMR (300 MHz, CDCl3) δ 5.34 (s, 1H), 3.98 (t, 2H, J=5.4 Hz), 3.52 (s, 3H), 2.84 (t, 2H, J=5.7 Hz), 2.45 (s, 3H); MS (ESI+) m/z 153.1 (M+H)

Provenance & Evidence