Reaction #1265372

Reaction equation

2,2,2-trichloroethyl chloroformate

5-amino-3-t-butyl-1-p-tolylpyrazole hydrochloride

water

NaOH

→

5-(2,2,2-Trichloroethoxycarbonyl)amino-3-t-butyl-1-p-tolylpyrazole

Solvents

EtOAc

Conditions

Workup

1. 1
   workup.STIRRINGThe mixture was stirred at room temperature for 2 h
2. 2
   Otherthe aqueous layer was separated from the EtOAc layer
3. 3
   WashThe EtOAc layer was washed with brine (2×0.9 L)
4. 4
   Dryingdried over MgSO4 (60 g)
5. 5
   FiltrationThe EtOAc layer was collected by filtration
6. 6
   workup.ADDITIONTo this solution, heptane was added
7. 7
   OtherA part of the solution was removed by distillation
8. 8
   OtherThe product was crystallized from the solution
9. 9
   Filtrationcollected by filtration
10. 10
    Otherdried in vacuum oven to constant weight

Procedure

A mixture of 5-amino-3-t-butyl-1-p-tolylpyrazole hydrochloride (300 g, 1.13 mol), water (0.9 L), EtOAc (2.1 L) and NaOH (117 g, 2.84 mol) was stirred between 5-15° C. for 30 min. To this mixture, 2,2,2-trichloroethyl chloroformate (342 g, 1.58 mol) was added over 1 h between 5-15° C. The mixture was stirred at room temperature for 2 h, and then the aqueous layer was separated from the EtOAc layer. The EtOAc layer was washed with brine (2×0.9 L) and dried over MgSO4 (60 g). The EtOAc layer was collected by filtration. To this solution, heptane was added. A part of the solution was removed by distillation. The product was crystallized from the solution, collected by filtration and dried in vacuum oven to constant weight. Yield: 409 g, 90%. 1H NMR (CDCl3) 7.40 (d, 2H), 7.30 (d, 2H), 6.40 (s, 1H), 4.80 (s, 2H), 2.40 (s, 3H), 1.40 (s, 9H). MS (EI) m/z 404 (M+).

Source