Reaction #2028885

Reaction equation

4-Sulfonamidophenylhydrazine hydrochloride

diketone

6-methyl-2-(trifluoroacetyl)tetralone

→

pyrazole

Yield 64.0%

4-[4,5-dihydro-7-methyl-3-(trifluoromethyl)-1H-benz[g]indazol-1-yl]benzenesulfonamide

Yield 64.0%

Solvents

ethanol

Conditions

Workup

1. 1
   TemperatureThe reaction was heated
2. 2
   Temperatureto reflux
3. 3
   TemperatureThe reaction mixture was cooled
4. 4
   Filtrationfiltered
5. 5
   ConcentrationThe filtrate was concentrated in vacuo
6. 6
   workup.DISSOLUTIONdissolved in ethyl acetate
7. 7
   Washwashed with water and with brine
8. 8
   Dryingdried over MgSO4

Procedure

4-Sulfonamidophenylhydrazine hydrochloride (1.80 g, 8.0 mmol) was added to a stirred solution of the diketone from Step 1 (1.86 g, 7.3 mmol) in ethanol (10 mL). The reaction was heated to reflux and stirred for 14.8 hours. The reaction mixture was cooled and filtered. The filtrate was concentrated in vacuo, dissolved in ethyl acetate, washed with water and with brine, dried over MgSO4 and reconcentrated in vacuo to give the pyrazole as a brown solid (1.90 g, 64%): mp 215°-218° C. 1H NMR (acetone-d6) 300 MHz 8.10 (d, 2H), 7.80 (d, 2H), 7.24 (s, 1H), 6.92 (d, 1H), 6.79 (br s, 2H), 6.88 (d,1H), 3.02 (m, 2H), 2.85 (m, 2H), 2.30 (s, 3H). 19F NMR (acetone-d6) 282 MHz −62.46 (s). High resolution mass spectrum Calc'd. for C19H17F3O2S: 408.0994. Found: 408.0989.

Source