3-(Dimethylamino)-1,2-diphenyl-2-propen-1-one → 4,5-Diphenyl-1-(ethoxycarbonylmethyl)-pyrazole

HRID 704819Notes

Reaction equation

HRID 704819 reaction equation
C[N:2](C)[CH:3]=[C:4]([C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)[C:5]([C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)=O.Cl.[NH:21]([CH2:23][C:24]([O:26][CH2:27][CH3:28])=[O:25])N>C(O)C>[C:13]1([C:4]2[CH:3]=[N:2][N:21]([CH2:23][C:24]([O:26][CH2:27][CH3:28])=[O:25])[C:5]=2[C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1

Participants

4

Reactant 2

HCID 865033-(Dimethylamino)-1,2-diphenyl-2-propen-1-oneHCID 11593468Acetic acid, 2-hydrazinyl-, ethyl ester, hydrochloride (1:1)

Product 1

HCID 146995514,5-Diphenyl-1-(ethoxycarbonylmethyl)-pyrazoleYield 87%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

When only the 4,5-diphenyl isomer is desired the following procedure is preferred. A mixture of 778 g (3.96 mol) deoxybenzoin, 580 mL (4.38 mol) of N,N-dimethylformamide dimethyl acetal, and 775 mL of methyl tert-butyl ether was refluxed for 3 hours. The reaction mixture was cooled on ice to 0°-5° C. The precipitated solid was collected by filtration, the filter cake washed with 250 mL of cold methyl tert-butyl ether twice and dried in vacuum chamber at 65° C. to afford 913 g (92%) of 3-(dimethylamino)-1,2-diphenyl-2-propen-1-one, mp 128°-133° C. A slurry of 913 g (3.64 mol) of 3-(dimethylamino)-1,2-diphenyl-2-propen-1-one in 3.4 L of absolute ethanol was treated with 618 g (4 mol) of ethyl hydrazinoacetate hydrochloride in one portion. The mixture was stirred at room temperature for 1 hour, filtered through diatomaceous earth, and the filtrate treated with 7 L of 50% aqueous ethanol with stirring. Cooling of the resultant solution to 0°-5° C. provided a white solid which was collected by filtration, washed with 250 mL of cold 50% ethanol twice and dried in vacuum at 40° C. to provide 970 g (87%) of ethyl 4,5-diphenyl-1H-pyrazole-1-acetate, mp 76°-80° C., containing none of the 3,4-diphenyl isomer detectable by GLC.

Workup

  1. filtrationfiltered through diatomaceous earth
  2. additionthe filtrate treated with 7 L of 50% aqueous ethanol
  3. stirringwith stirring
  4. temperatureCooling of the resultant solution to 0°-5° C.
  5. customprovided a white solid which
  6. filtrationwas collected by filtration
  7. washwashed with 250 mL of cold 50% ethanol twice
  8. customdried in vacuum at 40° C.

Sources & evidence

ORD record
ord-7a9853d7ed4a4b39ba4aa192e051dfe6
Source dataset
uspto-grants-1991_01
Patent number
US04988725

Reaction notes

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