Malonaldehyde-amine reactions

The addition of phenylisocyanate to aldehyde-derived enamines resulted in the formation of aminobutyrolactams (438,439). As aminal derivatives these produets can be hydrolyzed to the linear aldehyde amides and thus furnish a route to derivatives of the synthetically valuable malonaldehyde-acid system. With this class of reactions, a second acylation on nitrogen becomes possible and the six-membered cyclization products have been reported (440). Closely related to the reactions of enamines with isocyanates is the condensation of cyclohexanone with urea in base (441). 

Interaction of lipid oxidation products and amino compounds. Amino acids and primary amines may be involved in other reactions which could lead to the formation of compounds having the potential to undergo N-nitrosation. Malonaldehyde, produced as a result of oxidation of lipids, particularly polyunsaturated fatty acids, has been shown to react with amino acids to produce... 

The unsubstituted salt (6,R=R =H) is obtained in this way only in low yield. A much better method is available in the reaction of a salt of the bisanil, or better the bis(A-phenylanil) of malonaldehyde with ethylenedi-amine (73S791). 

The malonaldehyde-amine reaction has been extensively studied by Tappel and co-workers (2), by Csallany et al. (3), by Privett and co-workers (4), Knook et al. (5), Buttkus and Bose (6 ), as well as many others. As shown in Figure 1, malonaldehyde may react with a primary amine to produce an initial ene-amine Schiff base ( 7 ), then by further condensation with another amine, an amino-imino-propene compound. Heat and acid are required in the usual model reaction. The model compounds (lysine with malonaldehyde, for example) fluoresce between 430 and 470 nm when excited between 350 and 360 nm (8). These are typical of the "aging" pigments, the organic solvent-soluble lipofuscin in oxidizing tissue. 

Figure 1. Malonaldehyde-amine reactions. (Reproduced from Ref. 8. Copyright 1969, American Chemical Society.)...

Polyamide microcrystalline powders form measurable polymer-bound fluorescent reaction products with malonaldehyde from oxidizing lipids and with reducing sugars. The compounds form on the terminal amine groups which appear to exist in zwitterionic fields with carboxylate anions, as revealed by titration with acid, alkali, or benzoquinones. 

Figure 5. Reaction of lipid oxidation products such as malonaldehyde and amines.

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