反应详情

A suspension of 3.7 g (17.6 mmol) of 2,5-dimethoxy-3,4,6-trimethylbenzaldehyde and 5.0 g (53.2 mmol) of sodium pyruvate in 20 ml of methanol is treated with 0.1 g (1.8 mmol) of potassium hydroxide and the mixture is subsequently heated at reflux for 5 hours, whereby a yellow solution is obtained. The reaction mixture is poured on to ice-water and the resulting 4-(2',5'-dimethoxy-3',4',6'-trimethyphenyl)-2-keto-3-butenoic acid is precipitated by the addition of sulphuric acid while stirring. The suspension is stirred for 1 hour, filtered, the filter residue is washed with water and dried. In this manner there are obtained 4.9 g of 4-(2',5'-dimethoxy-3',4',6'-trimethylphenyl)-2-keto-3-butenoic acid in the form of a yellow powder of melting point 126°-127° C.

1. temperaturethe mixture is subsequently heated
2. temperatureat reflux for 5 hours
3. customwhereby a yellow solution is obtained
4. customthe resulting 4-(2',5'-dimethoxy-3',4',6'-trimethyphenyl)-2-keto-3-butenoic acid is precipitated by the addition of sulphuric acid
5. stirringThe suspension is stirred for 1 hour
6. filtrationfiltered
7. washthe filter residue is washed with water
8. customdried