Reacción #3716

Ecuación de reacción

propargyl bromide

2-(t-butyl)-5-(2,6-dichloro-4-pyridyl)-1,2,4-triazolin-3-one

K2CO3

→

2-(t-butyl)-5-(2,6-dichloro-4-pyridyl)-4-propargyl-1,2,4-triazolin-3-one

Disolventes

toluene

ethyl acetate

ethyl acetate

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe mixture was heated
2. 2
   workup.ADDITIONwas added
3. 3
   TemperaturaRefluxing
4. 4
   TemperaturaThe mixture was cooled
5. 5
   Lavadowashed with 25 mL of water
6. 6
   Secadodried over MgSO4
7. 7
   workup.WAITReomoval of the solvent left 2.18 g of crude product as a reddish solid
8. 8
   Otropurified by flash chromatography first on a silica gel column
9. 9
   Lavadoon a neutral alumina column eluted portionwise in both cases with ether hexane mixtures
10. 10
    workup.ADDITIONcontaining successively greater percentages of ether

Procedimiento

To 2.06 g (7.2 mmol) of crude 2-(t-butyl)-5-(2,6-dichloro-4-pyridyl)-1,2,4-triazolin-3-one were added 30 mL of ethyl acetate, 1 drop of water, and 1.00 g (7.30 mmol) of powdered K2CO3. The mixture was heated to reflux and after 15 min 1.10 g (7.4 mmol) of an 80% by weight solution of propargyl bromide in toluene was added. Refluxing was continued for 2.5 hours. The mixture was cooled, diluted with 175 mL of ethyl acetate, washed with 25 mL of water, and dried over MgSO4. Reomoval of the solvent left 2.18 g of crude product as a reddish solid. The crude product was combined with 0.69 g of material from another run and purified by flash chromatography first on a silica gel column and then on a neutral alumina column eluted portionwise in both cases with ether hexane mixtures containing successively greater percentages of ether to afford 0.97 g of 2-(t-butyl)-5-(2,6-dichloro-4-pyridyl)-4-propargyl-1,2,4-triazolin-3-one (Compound 1) as a white solid, m.p. 107°-109° C. 1H-NMR (CDCl3)∂1.6 (9H,s), 2.45 (1H,t), 4.6 (2H,d), 7.75 (2H,s).

Fuente