Hh. Zoorob et al., Synthesis of 5-(functionalized acyl)-1,3-dialkyl-substituted barbituric and 2-thiobarbituric acids, J HETERO CH, 38(2), 2001, pp. 359-363
A sodium derivative of 1,3-dimethylbarbituric acid or 1,3-diethyl-2-thiobar
bituric acid undergoes an efficient monoacylation at C5 by the reaction wit
h omega -chloroalkanoyl chloride or diacid dichloride in the presence of py
ridine in tetrahydrofuran. A nucleophilic displacement of the chlorine in a
5-chloroacetylbartiburate can be accomplished by using a one-pot procedure
. By contrast, a similar transformation of a 5-(chlorobutanoyl)barbituric a
cid requires intramolecular cyclization in the presence of a nonnucleophili
c base followed by treatment with a nucleophile of the resultant 5-[4,5 -di
hydro(3H)-2-furylidene]barbiturate.