2-Phenylacetophenone → 3-(Dimethylamino)-1,2-diphenyl-2-propen-1-one

HRID 1608282Notes

Reaction equation

HRID 1608282 reaction equation
[C:1]1([C:7]([CH2:9][C:10]2[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=2)=[O:8])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.CO[CH:18](OC)[N:19]([CH3:21])[CH3:20]>C(OC)(C)(C)C>[CH3:18][N:19]([CH3:21])[CH:20]=[C:9]([C:10]1[CH:11]=[CH:12][CH:13]=[CH:14][CH:15]=1)[C:7]([C:1]1[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1)=[O:8]

Participants

4

Reactant 2

HCID 99482-PhenylacetophenoneHCID 78373Dimethylformamide dimethyl acetal

Product 1

HCID 865033-(Dimethylamino)-1,2-diphenyl-2-propen-1-oneYield 92%

Reagents, catalysts & solvents 1

HCID 15413tert-Butyl methyl etherSolvent

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. temperaturewas refluxed for 3 hours
  2. temperatureThe reaction mixture was cooled on ice to 0°-5° C
  3. filtrationThe precipitated solid was collected by filtration
  4. washthe filter cake washed with 250 mL of cold methyl tert-butyl ether twice
  5. customdried in vacuum chamber at 65° C.

Sources & evidence

ORD record
ord-63324febadae4fadb60b5f8b7da1e178
Source dataset
uspto-grants-1989_09
Patent number
US04870095

Reaction notes

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