Phosphoric Acid → Zaleplon

HRID 1394387Notes

Reaction equation

HRID 1394387 reaction equation
C[N:2]([CH3:19])[CH:3]=[CH:4][C:5]([C:7]1[CH:8]=[C:9]([N:13]([CH2:17][CH3:18])[C:14](=[O:16])[CH3:15])[CH:10]=[CH:11][CH:12]=1)=O.N[C:21]1[C:25]([C:26]#[N:27])=C[NH:23][N:22]=1.P(=O)(O)(O)O>O.C(O)C>[CH3:18][CH2:17][N:13]([C:14]([CH3:15])=[O:16])[C:9]1[CH:10]=[CH:11][CH:12]=[C:7]([C:5]2[N:23]3[N:22]=[CH:21][C:25]([C:26]#[N:27])=[C:19]3[N:2]=[CH:3][CH:4]=2)[CH:8]=1

Participants

6

Reactant 3

HCID 1004Phosphoric AcidHCID 53395302N-(3-(3-(Dimethylamino)-1-oxo-2-propenyl)phenyl)-N-ethylacetamideHCID 178510443HCID 178510443, compound

Product 1

HCID 5719ZaleplonYield 90.2%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 962WaterSolvent

Procedure

Ethylacetamide 3 (260 g, 1 mol) and 3-amino-4-cyanopyrazole 4 (108 g, 1 mol) were dissolved in a mixture of water (7 L) and ethanol (4 L). Eighty five percent aqueous phosphoric acid (67 ml, 1 mol) was added and the mixture was stirred at room temperature for 8 h. The reaction mixture was then cooled to 5° C. and the crystalline product that formed was collected, washed with water and dried at 60° C. to afford zaleplon (275 g, 90.2%) which was 99.36 pure by HPLC and contained 0.21% regioisomer 5.

Workup

  1. temperatureThe reaction mixture was then cooled to 5° C.
  2. customthe crystalline product that formed
  3. customwas collected
  4. washwashed with water
  5. customdried at 60° C.

Sources & evidence

ORD record
ord-439677137b274c659f937bad5d09b7e9
Source dataset
uspto-grants-2008_03
Patent number
US07348429B2

Reaction notes

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