Phosphorus oxychloride → 4-chloro-1-methyl-1H-pyrazolo[3,4-d]pyrimidine

HRID 1703624Notes

Reaction equation

HRID 1703624 reaction equation
[CH3:1][N:2]1[C:6]2[N:7]=[CH:8][NH:9][C:10](=O)[C:5]=2[CH:4]=[N:3]1.P(Cl)(Cl)([Cl:14])=O>>[CH3:1][N:2]1[C:6]2=[N:7][CH:8]=[N:9][C:10]([Cl:14])=[C:5]2[CH:4]=[N:3]1

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 1354397141-Methyl-1,5-dihydropyrazolo(3,4-d)pyrimidin-4-one

Product 1

HCID 2197514-chloro-1-methyl-1H-pyrazolo[3,4-d]pyrimidineYield 60.5%

Procedure

80 g. of 1-methyl-1,5-dihydro-4H-pyrazolo[3,4-d]- pyrimidin-4-one are added to 300 ml. of phosphorus oxychloride and the mixture is refluxed. After distilling off the excess phosphorus oxychloride, the semi-solid residue is extracted with 3 × 100 ml. of boiling benzene. The benzene extracts are combined and concentrated to half-volume, then added to petroleum ether. After standing 12 hours in the refrigerator, the precipitated 1-methyl-4-chloropyrazolo[3,4-d]- pyrimidine is filtered under suction and recrystallized from cyclohexane to obtain 54 g. of white crystals, m.p. 93°-96° (yield 60.5%).

Workup

  1. distillationAfter distilling off the excess phosphorus oxychloride
  2. extractionthe semi-solid residue is extracted with 3 × 100 ml
  3. concentrationconcentrated to half-volume
  4. additionadded to petroleum ether
  5. filtrationthe precipitated 1-methyl-4-chloropyrazolo[3,4-d]- pyrimidine is filtered under suction
  6. customrecrystallized from cyclohexane
  7. customto obtain 54 g

Sources & evidence

ORD record
ord-44ad6199066c4b82895b0756e3205c31
Source dataset
uspto-grants-1978_11
Patent number
US04124764

Reaction notes

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