反应详情

45 g of N-(2-amino-5-methylbenzyl)-aminoacetaldehydedimethylacetal obtained in step (d) and 25 g of cyanogen bromide are heated under reflux in 500 ml of 95% ethanol for 18 hours. After the mixture containing 2-amino-3-(2,2-dimethoxyethyl)-6-methyl-3,4-dihydroquinazoline is cooled, 200 ml of 5 N hydrochloric acid are added, and the solution is left to stand for 2 hours at room temperature. After the reaction solution is concentrated in a vacuum, it is made alkaline with dilute caustic soda, whereupon the title compound crystallizes out, and is recrystallised from methanol or ethanol. M.p. 265° C.

1. temperatureis cooled
2. waitthe solution is left
3. concentrationAfter the reaction solution is concentrated in a vacuum, it
4. customwhereupon the title compound crystallizes out, and
5. customis recrystallised from methanol or ethanol