Acetic Anhydride → Ethyl 1-(4-chlorophenyl)-1,6-dihydro-4-methyl-6-oxopyrimidine-5-carboxylate

Participants

Reaction Steps

To a 2-l. three-necked flask are charged 250 g (0.88 mole) of ethyl 3-amino-2-(4-chlorophenylcarbamoyl)crotonate, 523 g. (3.54 moles) of triethyl orthoformate and 135 g (1.32 moles) of acetic anhydride. While stirring, reflux is initiated causing all solid to dissolve. After 15 to 16 hours at reflux, lower boiling liquid is distilled off (up to a head temperature of 90°-95° C.) and the dark reaction solution is subjected to rotary evaporation. Addition of the viscous residue to 4 l. of hot hexane with continued heating and agitation effects solidification. There is obtained 225 g (87%) of ethyl 1-(4-chlorophenyl)-1,6-dihydro-4-methyl-6-oxopyrimidine-5-carboxylate as a brown solid, m.p. 98°-100° C.

Provenance & Evidence