Reaction #657320

Reaction equation

NH4OH

water

4-bromo-3-phenyl-1H-pyrazole-5-amine

1,1,3,3-tetramethoxypropane

→

3-bromo-2-phenylpyrazolo[1,5-a]pyrimidine

Yield 76.6%

Solvents

acetic acid

Conditions

Workup

1. 1
   Extractionextracted with dichloromethane (3×100 mL)
2. 2
   DryingThe organic layer is dried over anhydrous magnesium sulphate
3. 3
   Filtrationfiltered
4. 4
   Concentrationconcentrated under reduced pressure
5. 5
   OtherThe crude material is purified by column chromatography

Procedure

To a solution of 4-bromo-3-phenyl-1H-pyrazole-5-amine (5.0 g, 0.02 mol) in acetic acid (50 mL) is added 1,1,3,3-tetramethoxypropane (4.14 g, 0.025 mol). The mixture is stirred at 110° C. for 1 h. The reaction mixture is then poured into water, basified with NH4OH and extracted with dichloromethane (3×100 mL). The organic layer is dried over anhydrous magnesium sulphate, filtered and concentrated under reduced pressure. The crude material is purified by column chromatography using silica gel in dichloromethane and ethyl acetate (1:0 to 95:5) as eluent and 4.2 g (75%) of 3-bromo-2-phenylpyrazolo[1,5-a]pyrimidine are obtained as a beige solid.

Source