反应详情

A solution of ethyl 2-(N-methyleneamino)-2-methylpropionate (10.3 g) in xylene was added during 1 hour to a solution of ethyl 2-(2-methoxyphenyl)acetoacetate (8.51 g) in xylene whilst heating under reflux. The rate of addition was controlled so as to equal the rate of azeotropic distillation (via a Dean and Stark separator). Additional xylene was then added and distillation continued for 3 hours. The mixture was evaporated in vacuo to give ethyl 2-[2,3-dihydro-5-(2-methoxyphenyl)-6-methyl-4-oxo-4H-1,3-oxazin-3-yl]-2-methylpropanoate (14.1 g), NMR 1.25(t,3H), 1.55(s,6H), 1.8(s,3H), 3.75(s,3H), 4.1 5(m,2H), 5.3(s,2H), 6.9-7.3(m,4H).

1. temperaturewhilst heating
2. temperatureunder reflux
3. additionThe rate of addition
4. distillationthe rate of azeotropic distillation (via a Dean and Stark separator)
5. additionAdditional xylene was then added
6. distillationdistillation
7. customThe mixture was evaporated in vacuo