Ethyl n-butylacetoacetate

To a solution of 59.5 gm of potassium hydroxide in 100 gm of an aqueous solution maintained at 75°C is added over a 1-hr period 12.3 gm of ethyl n-butylacetoacetate. Heating is continued for 5 hr with efficient stirring. 

Pyrimidine derivatives can be prepared in two ways. The first is the condensation of ethyl a-n-butylacetoacetate with thiourea in methanol in the presence of sodium methylate, and the reaction of the intermediate product (21) with methyl iodide. The compound 5-n-butyl-2-methylthio-4-hydroxy-6-methylpyrimidine (22) is formed, the reaction of which with dimethylamine acetate gives dimethirimol, and with ethylamine acetate, ethirimol, with a yield of 80%. 

In the second method, dimethirimol can be prepared in a single step with a yield of 50% by condensation of ethyl oc-n-butylacetoacetate with N,N-dimethyl-guanidine sulfate in a methanol-containing medium, in the presence of sodium methoxide (Elias et al.. 1968 Calderbank, 1971). 

---