Reaction Using Barbituric Acids

The barbituric acid derivatives, which have been known as hypnotic sedatives [136], were chosen as the first of the heterocyclic 1,3-dicarbonyl compounds for study because they consist of a cyclic diamide structure. The reaction of barbituric acid with 1,1-diphenylethene was conducted in acetic acid at room temperature in air using a catalytic amount of manganese(III) acetate. Surprisingly, solid products were easily obtained as a diastere-omixture, meso and racemic. Although the diastereomers could not be

Fig. 6 ORTEP drawing of 5,5-bis(2-hydroperoxyethyl)barbituric acid (R1=R2=Ph, R3 = H)

Scheme 23 Manganese(III)-catalyzed double 2-hydroperoxyalkylations of barbituric acids separated into individual isomers, the structure was determined by spectroscopy, elemental analysis, and finally X-ray crystallography. As a result, it was found that the solid products were not 1,2-dioxanes, but 5,5-bis(2-hydroperoxyethyl)barbituric acids (Fig. 6) [137].

Similar reactions of other barbituric acid derivatives with alkenes gave the corresponding 5,5-bis(2-hydroperoxyethyl)barbituric acids in quantitative yields (Scheme 23). Using thiobarbituric acid also afforded a similar bis(hydroperoxide) in good yield.

Reaction Using Pyrazolidine-3,5-diones

Derivatives of the pyrazolidine-3,5-diones possess a wide variety of biological and pharmaceutical activities along with other uses (e.g., color agents, photographic light-sensitive and thermal printing materials [138,139]). Es

Ri = r2 = Aryl.alkyl, R3 = Me,H, X = O (99-81%) R1 = r2 = Ph> r2 = Et, X = S (62%)
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