Acyl succinates

Condensation with Aldehydes and Ketones. Succinic anhydride and succinic esters in the presence of different catalysts react in the gas phase with formaldehyde to give citraconic acid or anhydride and itaconic acid (94—96). Dialkyl acyl succinates are obtained by reaction of dialkyl succinates with C 4 aldehydes over peroxide catalysts (97). 

The classical preparation of cyclobutyl ketones involves the base-catalyzed reaction of 1,3-dihaloalkanes with malonate esters. However, the initial product of this reaction is a cyclobutane carboxylic acid. S.D. Van Arnum and co-workers showed that cyclobutyl ketones can be efficiently synthesized starting from acyl succinates and using the... 

Cydopentane reagents used in synthesis are usually derived from cyclopentanone (R.A. Ellison, 1973). Classically they are made by base-catalyzed intramolecular aldol or ester condensations (see also p. 55). An important example is 2-methylcydopentane-l,3-dione. It is synthesized by intramolecular acylation of diethyl propionylsucdnate dianion followed by saponification and decarboxylation. This cyclization only worked with potassium t-butoxide in boiling xylene (R. Bucourt, 1965). Faster routes to this diketone start with succinic acid or its anhydride. A Friedel-Crafts acylation with 2-acetoxy-2-butene in nitrobenzene or with pro-pionyl chloride in nitromethane leads to acylated adducts, which are deacylated in aqueous acids (V.J. Grenda, 1967 L.E. Schick, 1969). A new promising route to substituted cyclopent-2-enones makes use of intermediate 5-nitro-l,3-diones (D. Seebach, 1977). 

Friedel-Crafts acylation of 3,3-dimethyl-2-indolinone by succinic anhydride gives 3,3-dimethyl-5-(3-catboxyptopionyl)-2-indoline, which is used as an intermediate in the preparation of inotropic agents for treatment of heart failure (94). Antibacterial phlotophenone derivatives have been prepared by Friedel-Crafts acylation with ptopanoyl chlotide (95). 

Friedel-Crafts acylation of unsaturated fatty acids can be carried out with succinic anhydride ia the presence of alkyl aluminium haUde (104). 

Friedel-Crafts Acylation. The Friedel-Crafts acylation procedure is the most important method for preparing aromatic ketones and thein derivatives. Acetyl chloride (acetic anhydride) reacts with benzene ia the presence of aluminum chloride or acid catalysts to produce acetophenone [98-86-2], CgHgO (1-phenylethanone). Benzene can also be condensed with dicarboxyHc acid anhydrides to yield benzoyl derivatives of carboxyHc acids. These benzoyl derivatives are often used for constmcting polycycHc molecules (Haworth reaction). For example, benzene reacts with succinic anhydride ia the presence of aluminum chloride to produce P-benzoylpropionic acid [2051-95-8] which is converted iato a-tetralone [529-34-0] (30). 

To minimize the gradual embrittlement that can occur on aging of cyanoacrylate adhesives, plasticizers are added. Some of the materials, which have been used as plasticizers, include phthalates, phosphonates, acyl esters, succinates, and cyano-acetates. The use of allyl, methallyl, and crotyl phthalates is also claimed to improve thermal resistance properties in addition to plasticizing the adhesive [23]. 

This is a crucial point because (as we will see) proton transport is coupled with ATP synthesis. Oxidation of one FADHg in the electron transport chain results in synthesis of approximately two molecules of ATP, compared with the approximately three ATPs produced by the oxidation of one NADH. Other enzymes can also supply electrons to UQ, including mitochondrial 5w-glyc-erophosphate dehydrogenase, an inner membrane-bound shuttle enzyme, and the fatty acyl-CoA dehydrogenases, three soluble matrix enzymes involved in fatty acid oxidation (Figure 21.7 also see Chapter 24). The path of electrons from succinate to UQ is shown in Figure 21.8. 

An interesting application of this reaction was the use of macro-molecular anhydrides, namely, styrene-maleic anhydride or vinyl acetate-maleic anhydride copolymers in the presence of perchloric acid as catalyst, these copolymers acylate mesityl oxide or d rpnone to macromolecular pyrylium salts which, with aryl substituents, are fluorescent.No crystalline products could be obtained from succinic anhydride because of the solubility and ease of decarboxylation. 

The second route employs acylation of tryptamine (259) as the first step by reacting it with succinic anhydride. After methylation with CH2N2, the resultant iVb-methoxysuccinyltryptamine (266) is transformed to the corresponding... 

Friedel-Crafts acylation can be carried out with cyclic anhydrides, in which case the product contains a carboxyl group in the side chain. When succinic... 

Advances in analytical procedures resulted in several reports on anthocyanins acy-lated with hydroxycinnamic acids (p-coumaric, caffeic, ferulic, sinapic, and 3,5-dihydroxycinnamic acids), hydroxybenzoic acids (p-hydroxybenzoic and gallic acids), and aliphatic acids (malonic, acetic, malic, oxalic, succinic and tartaric acids). However, not all of them were found in anthocyanins isolated from foods. Among the 44 fruits listed in Table 4.3.1, 15 presented acylated anthocyanins as did 12 of 13 vegetables shown in Table 4.3.3 and 2 of the 9 grains cited in Table 4.3.4. On the other hand, acylated anthocyanins were found in all grapes from Vitis species, although at different abundance levels, as can be seen in Table 4.3.2. A higher... 

An amine-terminated polyoxyalkylene having an average molecular weight from about 600 to about 10,000 can be acylated with a succinic acylating agent (e.g., hexadecenyl succinic anhydride or a Diels-Alder diacid) obtained from an unsaturated fatty acid [628,629] similarly, alkyl-aryl sulfonate salts [1319] can be used in lubrication. 

A classical procedure for fusing a six-membered ring to an aromatic ring uses succinic anhydride or a derivative. An intermolecular acylation is followed by reduction and an intramolecular acylation. The reduction step is necessary to provide a more reactive ring for the second acylation. 

Ester formation from polysaccharides can be achieved in several ways First by acylation of the OH groups with carboxylic or sulfonic acid azolides, second by converting the OH groups with imidazole carboxylates into carbonates, and third by reaction of an acid leash on the polysaccharide with an alcohol by means of CDI or analogous azolides. The acid leash might, for example, be a succinate attached to the polysaccharide. 

Almost every major structural class discussed to date has featured at least one nonsteroidal antiinflammatory carboxylic acid. It is thus perhaps not surprising to find a dibenzoheterocycle serving as the nucleus for one of these agents, furobufen (34). Straightforward Friedel-Crafts acylation of dibenzo-furan (33) with succinic anhydride affords a mixture of 2- and 3-acylated products, with the latter predominating. The mixture is esterified with methanol, and the methyl ester of the 3-isomer is separated by fractional crystallization. Hydrolysis back to the... 

Acylation of diethyl succinate by ethyl trifluoroacetate in presence of sodium hydride and in absence of a solvent is hazardous, fire or explosion occurring on 2 occasions some 10-20 min after adding a tittle of the succinate to the hydride-trifluoroacetate premixture at 60°C. Presence of a solvent appears to eliminate the hazard. 

Fig. 14.1. Role ofthe pyruvate dehydrogenase complex (PDC) during aerobic/ anaerobic transitions in the development of Ascaris suum. PDC, pyruvate dehydrogenase complex AD, acyl CoA dehydrogenase ER, enoyl CoA reductase FR, fumarate reductase SDH, succinate dehydrogenase.

Modification of amines with maleic anhydride is done essentially the same as that described for succinic anhydride (this section, Part A), except the pH of the reaction should be kept alkaline (pH 8-9) at all times to prevent unwanted de-acylation. Deblocking of maleylated amines can be accomplished according to the following procedure of Butler et al. (1967). 

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