Synthesis of novel 2,3-substituted-2,4-dihydro-pyrazolo[4,3-d]pyrimidine-5,7-diones

Tetrahedron Letters

Volumn 50, Issue 46, 2009, Pages 6223-6227

  Brady, Thomas ^a   Vu, Khang ^a   Barber, Jack R ^a   Ng, Shi Chung ^a   Zhou, Yuefen ^a  

^a CytRx Corporation   (United States)

Author keywords

1,4 Dihydro pyrazolo 4,3 d pyrimidine 5,7 dione derivatives; 2,3 Substituted 2,4 dihydro pyrazolo 4,3 d pyrimidine 5,7 diones; 2,4 Dihydro pyrazolo 4,3 d pyrimidine 5,7 dione derivatives; Assignment of regio isomer structures; Single crystal X ray structure analysis

Indexed keywords

ADENOSINE A1 RECEPTOR ANTAGONIST; BLOOD CLOTTING FACTOR 10A INHIBITOR; PURINE ANTAGONIST;

ARTICLE; CYCLIZATION; DIAZOTIZATION; DRUG SYNTHESIS; ISOMER; METHYLATION; PROTON NUCLEAR MAGNETIC RESONANCE; SUBSTITUTION REACTION; X RAY CRYSTALLOGRAPHY;

EID: 70349605585     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2009.08.098     Document Type: Article

References (19)

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16. 3, 400 MHz): δ 0.96 (t, 3H, J = 6 Hz), 1.23 (t, 3H, J = 5.6 Hz), 1.38 (m, 2H, J = 6 Hz), 1.90 (m, 2H, J = 6 Hz), 4.09 (q, 2H, J = 5.6 Hz), 4.60 (t, 2H, J = 6 Hz), 7.42-7.36 (m, 2H), 7.63 (dd, 1H, J = 6, 1.2 Hz), 7.75 (m, 1H), 10.11 (br s, 1H).
17. +) to afford the pyrazole urea intermediate (10a). The solvent was removed under reduced pressure and the residue was taken up in THF (10 mL), potassium tert-butoxide (2.0 M in THF, 0.5 mL, 1 mmol) was added and the reaction was stirred for 30 min at ambient temperature. The solution was then diluted with aqueous 1.0 N HCl (100 mL) and extracted with ethyl acetate (3 × 75 mL). The combined organic extracts were dried over sodium sulfate, filtered, and concentrated.
18. 3 gas was generated by slowly adding concentrated HCl to aqueous slurry of sodium nitrite in a 3-necked flask via an additional funnel. One of the necks was covered with a stopper and the other one was directed, via Tygon tubing, to a syringe immersed in the solvent in the reaction flask.
19. Crystallographic data (excluding structure factors) for the structures in this Letter have been deposited with the Cambridge Crystallographic Data Centre as supplementary publications nos. The deposition number is CCDC 730905.