反应详情

A 22 liter, three-necked flask was charged with 634 g (3.5 moles) of the β-hydroxyamide of part (a) and 5.2 liters of isopropyl acetate. The flask was cooled externally in a bath with tap water (10°-15° C.) and 390 ml (5.25 moles) of thionyl chloride was added to the stirred suspension over 45 minutes. A mild exotherm was apparent, but the temperature was maintained between 25° and 30° C. After stirring 2 hr at ambient temperature, the suspension was filtered and the cake washed with isopropyl acetate. After air drying for two hours, the solid was transferred to a 22 liter flask and dissolved in 1.4 liters of water. The solution was treated with saturated sodium bicarbonate solution until slightly basic. A heavy white precipitate formed during the addition. The suspension was filtered and the resulting white solid was washed with cold water and dried overnight in vacuo at 65° C. A total of 522 g (91.5%) of the 4,5-dihydro-2-(4-hydroxyphenyl)oxazole, m.p. 209°-211° C., was obtained.

1. additionwas added to the stirred suspension over 45 minutes
2. temperaturethe temperature was maintained between 25° and 30° C
3. filtrationthe suspension was filtered
4. washthe cake washed with isopropyl acetate
5. customAfter air drying for two hours
6. customthe solid was transferred to a 22 liter flask
7. dissolutiondissolved in 1.4 liters of water
8. additionThe solution was treated with saturated sodium bicarbonate solution until slightly basic
9. customA heavy white precipitate formed during the addition
10. filtrationThe suspension was filtered
11. washthe resulting white solid was washed with cold water
12. customdried overnight in vacuo at 65° C