Beta-dicarbonyl compounds

This sequence is equally applicable to keto esters. Thus, condensation of guanidine with ethyl acetoacetate gives the pyrimidone, 134. Elaboration as above gives the pyrimidine, IJ5 acylation with the sulfonyl chloride (88) followed by hydrolysis yields sulfamerazine (107). Reaction of guanidine with beta dicarbonyl compounds gives the pyrimidine directly. Condensation of the base with acetonyl acetone affords the starting amine for sulfadimidine (108). ... 

Putilova ES, Troitskii NA, Zlotin SG (2005) Reaction of aromatic aldehydes with beta-dicarbonyl compounds in a catalytic system piperidinium acetate - l-butyl-3-methylimida-zolium tetrafluoroborate ionic liquid. Russ Chem Bull 54 1233-1238... 

Garcia Gonzalez, F., and Gomez Sanchez, A., Reactions of Amino Sugars with beta-Dicarbonyl Compounds, 20, 303-355 Goepp, Rudolph Maximilian, Jr. See Lohmar, Rolland. 

Odani, H., Shinzato, T., Matsumoto, Y., Usami, J., and Maeda, K. 1999. Increase in three alpha, beta-dicarbonyl compound levels in human uremic plasma Specific in vivo determination of intermediates in advanced Maillard reaction. Biochem. Biophys. Res. Commun. 256 89-93. 

Formation of Pyrimidines from beta-Dicarbonyl and 1,1-Diamino Compounds. Yet another application of the amine-carbonyl reaction is viewed in the constmction of the pyrimidine ring. Here a 1,1-diamino compound reacts with a beta-dicarbonyl compound, as is outlined in Scheme 4.12. 

Pyrazoles have a high degree of aromaticity with a Bird Ia of 90. They also are involved in a tautomeric equilibrium, with the NH tautomer being preferred (Scheme 9.31). Generally, they are synthesized from a preformed compound with a N-N bond, usually a hydrazine. Reaction with a beta-dicarbonyl compound gives the pyrazole structure. 

Khan AT, Parvin T, Choudhury LH (2008) Effects of Substituents in the beta-Position of 1,3-dicarbonyl compounds in bromodimethylsulfonium bromide-catalyzed multicomponent reactions a facile access to functionalized piperidines. J Org Chem 73 8398-8402... 

Acidities of / -Dicarbonyl Compounds Table 22-1 compares the acidities of some carbonyl compounds with the acidities of alcohols and water. Notice the large increase in acidity for compounds with two carbonyl groups beta to each other. The a protons of the jS-dicarbonyl compounds are more acidic than the hydroxyl protons of water and alcohols. This enhanced acidity results from increased stability of the enolate ion. The negative charge is delocalized over two carbonyl groups rather than just one, as shown by the resonance forms for the enolate ion of diethyl malonate (also called malonic ester). 

Like the aldol and the Claisen, the Michael reaction also involves an enolate, so the mechanism begins with the deprotonation of an alpha carbon. In the Michael reaction, however, the electrophile is not an ordinary carbonyl, but an a,P-unsaturated carbonyl. Attack of the stable enolate nucleophile occurs at the beta carbon of the a,P-unsaturated carbonyl (called a 1,4-addition or conjugate addition or even Michael addition) to give an enolate intermediate. Protonation at the alpha carbon of the enolate gives the final product, a 1,5-dicarbonyl compound. 

A typical retrosynthesis of a 1,5-dicarbonyl compound involves making a disconnection from one of the alpha carbons between the two carbonyls. The alpha carbon will be introduced as a nucleophilic enolate the other carbon needs to be electrophilic. Since the electrophilic carbon is beta to a carbonyl, the starting material is derived by installing a double bond between the alpha and beta carbons to make an a,P-unsaturated carbonyl. 

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