6-(4-Tert-butyl-phenyl)-4-oxo-4,5-dihydro-pyrazolo[1,5-a]pyrazine-2-carboxylic acid → 6-(4-tert-butyl-phenyl)-5H-pyrazolo[1,5-a]pyrazin-4-one

HRID 2272955Notes

Reaction equation

[C:1]([C:5]1[CH:10]=[CH:9][C:8]([C:11]2[NH:12][C:13](=[O:23])[C:14]3[N:15]([N:17]=[C:18](C(O)=O)[CH:19]=3)[CH:16]=2)=[CH:7][CH:6]=1)([CH3:4])([CH3:3])[CH3:2]>N1C2C(=CC=CC=2)C=CC=1.[Cu]>[C:1]([C:5]1[CH:6]=[CH:7][C:8]([C:11]2[NH:12][C:13](=[O:23])[C:14]3[N:15]([N:17]=[CH:18][CH:19]=3)[CH:16]=2)=[CH:9][CH:10]=1)([CH3:4])([CH3:2])[CH3:3]

Participants

Conditions

Temperature: 190 °C

Procedure

28.9 mg (0.454 mmol) Copper powder is added to a solution of 70.7 mg (0.227 mmol) 6-(4-tert-butyl-phenyl)-4-oxo-4,5-dihydro-pyrazolo[1,5-a]pyrazine-2-carboxylic acid in 2 ml quinoline. The mixture is stirred at 190° C. for 20 hours. Quinoline is distilled off under vacuum and the residue is chromatographed on a silica gel column with cyclohexane/ethyl acetate as eluent to give 6-(4-tert-butyl-phenyl)-5H-pyrazolo[1,5-a]pyrazin-4-one as colourless crystals; HPLC/MS: 1.88 (C), [M+H] 268; 1H NMR (400 MHz, DMSO-d6) δ [ppm] 11.49 (s, 1H), 8.03 (s, 1H), 7.92 (d, J=2.2, 1H), 7.69 (d, J=8.5, 2H), 7.49 (d, J=8.6, 2H), 7.01 (d, J=1.6, 1H), 1.32 (s, 9H).

Workup

distillationQuinoline is distilled off under vacuum
customthe residue is chromatographed on a silica gel column with cyclohexane/ethyl acetate as eluent

Sources & evidence

ORD record: ord-5007cc86f459434dbcf66104422fd013
Source dataset: uspto-grants-2015_09
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09120805B2

Reaction notes

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