反应详情

Methyl 3-hydroxy-5-methyl-2-thiophenecarboxylate (20.0 g, 116 mmoles) is dissolved in acetonitrile (450 mL) under argon. Triisopropylisourea (86.6 g, 465 mmoles) is added and the mixture stirred and heated under reflux. After 24 hours the mixture is cooled and the precipitate filtered off, rinsed with cold MeCN and discarded. The filtrate is stripped of solvent by rotary evaporator, then the excess triisopropylisourea is removed by distillation under reduced pressure. The remaining residue is dissolved in a small amount of ethyl acetate, cooled, filtered, and passed through a short column of silica gel. Evaporation of the effluent under reduced pressure leaves the product as an oil (18.8 g) sufficiently pure for further use.

1. temperatureheated
2. temperatureunder reflux
3. temperatureAfter 24 hours the mixture is cooled
4. filtrationthe precipitate filtered off
5. washrinsed with cold MeCN
6. customThe filtrate is stripped of solvent by rotary evaporator
7. customthe excess triisopropylisourea is removed by distillation under reduced pressure
8. dissolutionThe remaining residue is dissolved in a small amount of ethyl acetate
9. temperaturecooled
10. filtrationfiltered
11. customEvaporation of the effluent under reduced pressure