- Mono C-alkylation and mono C-benzylation of barbituric acids through zinc/acid reduction of acyl, benzylidene, and alkylidene barbiturate intermediates
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Through systematic exploration of reaction conditions, very efficient preparative procedures for obtaining large quantities of substituted 5-alkyl and 5-benzylbarbituric acids were developed. The procedure involves a two step preparation in which the second step is zinc dust/acid reduction. For preparation of 5-alkylbarbiturates, the first step is the preparation of either 5-acyl or 5-alkylidenebarbiturate. If 5-benzylbarbiturate is the target product, then the first step includes the preparation of 5-benzylidene. Regardless of the nature of the first step, all reactions presented synthetic yields around 90% and isolation and purification involves only crystallization.
- Jursic, Branko S.,Stevens, Edwin D.
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p. 2203 - 2210
(2007/10/03)
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- Reaction of 1,3-Dialkylbarbituric acids with aliphatic amines
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On heating triethylammonium 1,3-dimethylbarbiturate, 1,3-dimethylthiobarbiturate, and 1,3-diphenylbarbiturate occurs dealkylation of triethylamine to afford in high yields the corresponding 5-ethyl substituted barbituric acids. The cleavage of alkyl groups happened also efficiently with tributyl, tribenzyl, and dimethylbenzylammonium salts, and less efficiently with trimethylammonium and diethylammonium salts. These reactions are characteristic only of 1.3-disubstituted barbituric acids; the barbituric acid and its 1-alkyl derivatives under these conditions suffer degradation.
- Krasnov
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p. 280 - 284
(2007/10/03)
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