1-Propanol → Propyl 3-amino-1H-furo[3,2-c]pyrazole-5-carboxylate

HRID 1723930Notes

Reaction equation

HRID 1723930 reaction equation
[C:1]([C:3]1[O:7][C:6]([C:8]([O:10][CH3:11])=[O:9])=[CH:5][C:4]=1[NH:12][N:13]=C(C1C=CC=CC=1)C1C=CC=CC=1)#[N:2].S(=O)(=O)(O)O.[CH2:32](O)[CH2:33]C>>[NH2:2][C:1]1[C:3]2[O:7][C:6]([C:8]([O:10][CH2:11][CH2:32][CH3:33])=[O:9])=[CH:5][C:4]=2[NH:12][N:13]=1

Participants

4

Reactant 3

HCID 10311-PropanolHCID 1118Sulfuric AcidHCID 86606584Methyl 5-cyano-4-[2-(diphenylmethylene)hydrazino]-2-furoate

Product 1

HCID 57358414Propyl 3-amino-1H-furo[3,2-c]pyrazole-5-carboxylate

Procedure

To a solution of 56.01 g (0.1624 mol) of methyl 5-cyano-4-[2-(diphenylmethylene)hydrazino]-2-furoate in 1.12 L of n-propanol was slowly added 115 mL (2.1 mol) of 98% sulfuric acid. The resulting mixture was refluxed for 2 hours obtaining a clear brown solution. The reaction mass was concentrated under reduced pressure to a small volume, cooled to 0/+4° C. and slowly diluted with 1.1 L of 25% trisodium citrate dihydrate solution over a period of 90 min. under efficient stirring. The mixture (pH=4) was extracted three times with 600 mL of cyclohexane. The organic extracts were discarded while the aqueous layer was cooled to 0/+4° C. and brought to pH 6-7 by carefully adding 1 L of 10% aqueous sodium bicarbonate and, finally, 82 mL of N-methylmorpholine. The resulting suspension was aged for 4 hours at 0/+2° C. and then filtered and washed thoroughly with water affording, after drying, 21.35 g of product as light brown solid.

Workup

  1. temperatureThe resulting mixture was refluxed for 2 hours
  2. customobtaining a clear brown solution
  3. concentrationThe reaction mass was concentrated under reduced pressure to a small volume
  4. temperaturecooled to 0/+4° C.
  5. additionslowly diluted with 1.1 L of 25% trisodium citrate dihydrate solution over a period of 90 min. under efficient stirring
  6. extractionThe mixture (pH=4) was extracted three times with 600 mL of cyclohexane
  7. temperaturewas cooled to 0/+4° C.
  8. additionby carefully adding 1 L of 10% aqueous sodium bicarbonate
  9. filtration/+2° C. and then filtered
  10. washwashed thoroughly with water affording
  11. customafter drying

Sources & evidence

ORD record
ord-91645a21faa543b4bbe41ee02d334c3c
Source dataset
uspto-grants-2009_02
Patent number
US07485661B2

Reaction notes

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