1,1-Dicarboxylic acids, decarboxylation esters

Claisen ester condensation, 6, 279 Thiazolecarboxylic acid chlorides reactions, 6, 279-280 Thiazolecarboxylic acid hydrazides synthesis, 6, 280 Thiazolecarboxylic acids acidity, 6, 279 decarboxylation, 6, 279 reactions, S, 92 6, 274 Thiazole-2-carboxylic acids decarboxylation, S, 92 Thiazole-4-carboxylic acids stability, S, 92 Thiazole-5-carboxylic acids decarboxylation, S, 92 Thiazole-4,5-dicarboxylic acid, 2-amino-diethyl ester reduction, 6, 279 Thiazole-4,5-dicarboxylic acids diethyl ester saponification, 6, 279 Thiazolediones diazo coupling, 5, 59 Thiazoles, 6, 235-331 ab initio calculations, 6, 236 acidity, S, 49 acylation, 6, 256 alkylation, S, 58, 73 6, 253, 256 analytical uses, 6, 328 antifogging agents... 

Hagiya et al. recently reported [20] the new decarboxylation catalyst of chrysanthemum dicarboxylic acid monomethyl ester (46) to give ethyl (Z)-norchrysanthemate (EIZ = 4/96) in 59% yield. This method efficiently gives (Z)-(l R)-lrans-norchrysanthemic acid, but the yield is still moderate and the starting chrysanthemum dicarboxylic acid monomethyl ester is not a commercial product (Scheme 7). 

Carbon-carbon bond formation /3 to sulfur is little known for the monocycles, again perhaps because of poor accessibility of precursors, but is very common for the preparation of thiochromanones. Frequently, a dicarboxylic acid or ester is cydized under basic conditions, and decarboxylation affords the keto compound, from which the unsubstituted system may readily be obtained (76JCS(P1)749). A more modern reaction is shown in equation (81) (73TL4315). Me... 

Olefinic dicarboxylic acids and esters from the Knoevenagel condensation are readily decarboxylated to olefinic acids. Decarboxylation frequently occurs during the condensation and is discussed elsewhere (method 37). 

Electrophilic substitution of the ring hydrogen atom in 1,3,4-oxadiazoles is uncommon. In contrast, several reactions of electrophiles with C-linked substituents of 1,3,4-oxadiazole have been reported. 2,5-Diaryl-l,3,4-oxadiazoles are bromi-nated and nitrated on aryl substituents. Oxidation of 2,5-ditolyl-l,3,4-oxadiazole afforded the corresponding dialdehydes or dicarboxylic acids. 2-Methyl-5-phenyl-l,3,4-oxadiazole treated with butyllithium and then with isoamyl nitrite yielded the oxime of 5-phenyl-l,3,4-oxadiazol-2-carbaldehyde. 2-Chloromethyl-5-phenyl-l,3,4-oxadiazole under the action of sulfur and methyl iodide followed by amines affords the respective thioamides. 2-Chloromethyl-5-methyl-l,3,4-oxadia-zole and triethyl phosphite gave a product, which underwent a Wittig reation with aromatic aldehydes to form alkenes. Alkyl l,3,4-oxadiazole-2-carboxylates undergo typical reactions with ammonia, amines, and hydrazines to afford amides or hydrazides. It has been shown that 5-amino-l,3,4-oxadiazole-2-carboxylic acids and their esters decarboxylate. 

Fronchimont Reaction. By the action of f CN on a-bromo acids or esters, a-cyano-a,j8-dicarboxylic acid derivatives are formed which on hydrolysis and decarboxylation yield a,/8 dicarboxylic acids ... 

Only the 1-benzyl-vic-triazole, crysts(from eth at 20°), mp 61°, appears to have been prepd and reported in the literature. Curtius Raschig(Ref 2) prepd 1-benzyl-vic-triazole by the reaction of benzyl azide with the methyl ester of acetylene-dicarboxylic acid, followed by sapon and decarboxylation. Wiley et al(Ref 3) prepd the compd directly and in better yield from acetylenedicar-boxylic acid, followed by decarboxylation to 1 -benzyl-vic-triaZole(77% yield)... 

The C8 aldehyde ester may be produced by cleavage of the 9-hydroperoxide of ethyl llnoleate followed by terminal hydroperoxidation. Further oxidation would produce the corresponding dicarboxylic acid which upon decarboxylation would give rise to ethyl heptanoate. The 8-alkoxy radical may also decompose to give the C7 alkyl radical, which would yield ethyl heptanoate or form a terminal hydroperoxide, and so on. Polymerization, both intra- and intermolecular, is also a major reaction in high temperature oxidation. Combination of alkyl, alkoxy, and peroxy radicals yields a variety of dimeric and polymeric compounds with C-O-C or C-O-O-C crosslinks. 

Synthetic and degradative use has been made in several instances of the easy decarboxylation of phenanthridine-6-carboxylio acids.30, 80, 324 The corresponding iV-oxide is decarboxylated by heating in aqueous sulfuric acid.77 Phenanthridine-3,8-dicarboxylic acids are more resistant to decarboxylation, which can be achieved (in poor yield) by heating with copper powder in quinoline.194 The usual carboxyl derivative inter con versions (esterification, amide formation, ester and amide hydrolyses, etc.) proceed normally with both phenanthridine-6-carboxylic acid and its A-oxide,77, 232, 352 although an unsuccessful attempt to prepare 6-acetylphenanthridine from the acid with methyllithium has been reported.232... 

The reaction of isatins 9 with halogen-substituted acids or their esters 61 takes place even at room temperature. The obtained dicarboxylic acids 62 are decarboxylated in situ, and the final products are derivatives of 3-hydroxy-4-quinolinecarboxylic acid 63 [48, 49],... 

Cyclizative condensations based on aldol-type reactions which conform to the IIbd pattern have also been developed. Condensation of bis(alkoxycarbonylmethyl)amines or bis(cyanomethyl)amines with benzil affords 3,4-diarylpyrrole-2,5-dicarboxylic acid esters or nitriles. These reactions frequently lead to partial hydrolysis of at least one of the alkoxycarbonyl substituents and if the 3,4-diarylpyrrole is the ultimate objective, work-up involving complete hydrolytic decarboxylation is appropriate (equation 119) (61LA(639)102, 65JOC859). 

The oxidation of 1,4-dicarboxylic acids with LTA in benzene results in double decarboxylation with the formation of a double bond (equation 16). Similarly, the pyrolysis of the di-r-butyl peroxy esters of... 

The oxidation of 1,4-dicarboxylic acids with LTA in benzene results in double decarboxylation with the formation of a double bond (equation 16). Similarly, the pyrolysis of the di-r-butyl peroxy esters of 1,4-dicarboxylic acids in high boiling solvents leads to the formation of double bonds (equation 17). The method is especially useful in so far as 1,4-diacids are readily available from Diels-Alder reactions using derivatives of mtdeic and fumaric acid as the dienophile. Apparently, application of the 0-acyl thiohydroxamate method to 1,4-diacids does not result in the formation of double bonds but rather in the product of double decarboxylative rearrangement (Section S.4.6.1). ... 

Alkylation of malonic ester by one-half equivalent of an a,-polymethylene bromide gives an a,a,o), o)-tetracarboxylic ester which is hydrolyzed and decarboxylated to an a, fxi-dicarboxylic acid having four more carbon atoms than the dibromide. Good descriptions include those for 1,12-... 

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