Acetic acid substituted, synthesis

CF3CO2H. Colourless liquid, b.p. 72-5 C, fumes in air. Trifluoroacetic acid is the most important halogen-substituted acetic acid. It is a very strong acid (pK = o y) and used extensively for acid catalysed reactions, especially ester cleavage in peptide synthesis. 

A wide variety of /3-lactams are available by these routes because of the range of substituents possible in either the ketene or its equivalent substituted acetic acid derivative. Considerable diversity in imine structure is also possible. In addition to simple Schiff bases, imino esters and thioethers, amidines, cyclic imines and conjugated imines such as cinnamy-lidineaniline have found wide application in the synthesis of functionalized /3-lactams. A-Acylhydrazones can be used, but phenylhydrazones and O-alkyloximes do not give /3-lactams. These /3-lactam forming reactions give both cis and /raMS-azetidin-2-ones some control over stereochemistry can, however, be exercised by choice of reactants and conditions. 

The synthetic importance of the malonic ester synthesis follows from the fact that the substituted malonic ester can easily be hydrolyzed, and subsequently decarboxylates to yield a substituted acetic acid 9. This route to substituted acetic acids is an important method in organic synthesis ... 

Malonic esters have two ester groups, each of which may react as in the acetoacetic ester synthesis due to their similar structure (see the preceding section). The malonic ester synthesis provides a method for preparing a substituted acetic acid. Figure 15-14 shows the structure of one type of malonic ester. Figure 15-15 outlines the basic malonic ester synthesis. May repeat in that figure refers to the reaction with a second molecule of RX (or R X). 

MALONIC ESTER SYNTHESIS OF R-SUBSTITUTED ACETIC ACIDS,... 

Synthesis of substituted acetic acids via acetoacetic ester Acetoacetic ester, an ester formed by the self-condensation of ethyl acetate via a Claisen condensation, has the following structure ... 

Synthesis of substituted acetic acid via malonic ester Malonic ester is an ester formed by reacting an alcohol with malonic acid (propanedicarboxylic acid). Following is the structure of diethyl malonate ... 

Synthesis of substituted acetic acids via acetoacetic ester... 146 Synthesis of substituted acetic acid via malonic ester. .. 150 a halo acids, a hydroxy acids, and a, (3 unsaturated acids.. .153... 

Malonic Ester Synthesis of Substituted Acetic Acids... 

Malonic ester synthesis (makes substituted acetic acids Chapter 22)... 

The product of a malonic ester synthesis is a substituted acetic acid, with the substituent being the group used to alkylate malonic ester. In effect, the second carboxyl group is temporary, allowing the ester to be easily deprotonated and alkylated. Hydrolysis and decarboxylation remove the temporary carboxyl group, leaving the substituted acetic acid. 

Show how the malonic ester synthesis makes substituted acetic acids, and how the acetoacetic ester synthesis makes substituted acetones. Give mechanisms for these reactions. 

MALONIC ESTER SYNTHESIS OF R-SUBSTITUTED ACETIC ACIDS, RCH2COOH OR R(R ) CHCOOH (R could R)... 

The malonic ester synthesis converts a primary or secondary alkyl halide into a carboxylic acid with two more carbons (a substituted acetic acid). Identify the component that originates from malonic ester (the acid component). The rest of the molecule comes from the alkyl halide, which should be primary or methyl. 

Vinamidinium salts are important intermediates in the synthesis of heterocycles. The 2-chloro-l,3-bis(dimethylamino)trimethinium hexafluorophosphate salt has been used in the preparation of the highly selective Cox-2 inhibitor etoricoxib (Scheme 1). This method describes a straight-forward preparation of the hexafluorophosphate salt which is a crystalline, thermally and shock-stable, non-hygroscopic solid. The submitters have extensively studied the preparation of vinamidinium salts and demonstrated that the method is applicable to substituted acetic acids that contain an electron-withdrawing group (Table 1)." The annulation reaction is also general and useful for the preparation of pyridines, pyridones and pyridine N-oxides. ... 

The nitro substitution products of naphthalene are easily prepared by the action of nitric acid on the hydrocarbon. By such direct nitration the product obtained is alpha-nitro naphthalene. This is proven by the following series of reactions. Nitro-naphfhalene by reduction yields amino naphthalene, naphthylamine, which by the diazo reaction yields hydroxy naphthalene, naphthol. Now the naphthol so obtained is identical with the one resulting from the phenyl vinyl acetic acid synthesis (p. 768) and this must be the alpha compound. 

Merour, J.Y., Coadou, J.Y., and Tatibouet, E, Syntheses of 2(5)-substituted l-acetyl-3-oxo-2,3-dihy-droindoles, 3-acetoxy-l-acetylindoles, and of 2-methyl-5-methoxyindole-3-acetic acid. Synthesis, 1053, 1982. 

Certain acid derivatives are capable of reactions involving intermediate carbanions. The malonic ester synthesis is used to synthesize substituted acetic acids. The reaction involves abstraction of... 

Means to improve the material properties of plastics have been sought for decades. Improvement has sometimes come in the form of compounds such as mineral fillers, antioxidants, and flame-retardants. One of the first searches for an improved material was centered on cellulose nitrate. Cellulose nitrate is colorless and transparent, which enabled it to be used as photographic film. However, it is extremely flammable, and its early use in motion picture film and concomitant exposure to hot lights led to numerous fires. In 1900, Henri Dreyfus substituted acetic acid for nitric acid in the synthesis of cellulose nitrate, and created instead a less flammable material, cellulose acetate. Today, polymers are often halogenated in order to achieve flame-retardation. 

The net polar effect is directed along the axis of the molecule in line with the nitrogen lone pair. Table 10 collects some up values. The Roberts and Moreland approach, while giving excellent values absolutely independently of resonance or steric effects requires the synthesis of some very challenging molecules and the same might be said of Grob s method. Taft and Lewis [51] defined a a, value which is very accessible substituted acetic acids are readily available as are their ionisation... 

Further, CC has been used for the synthesis of /3-lactams <1981S209>. The procedure involves the reaction of an imino compound with a substituted acetic acid in the presence of TCT and TEA /3-lactams are obtained in good yields (Scheme 45). 

The condensation of salicylaldehyde or its derivatives with various derivatives of ethyl acetate in the presence of piperidine led to the synthesis of coumarins 95 in 55-94% yields under solvent-free conditions using MWI. Similarly, the benzo analogs 96 were prepared in 75-82% yields from 2-hydroxy-1-naphthaldehyde within 3-lOmin (Scheme 19) (98JCR(S)468). However, naphtho[2,l-Z ]pyran-3-ones 96 were prepared in 58-67% yields from the same aldehyde and substituted acetic acids under MWI for 6-8 min but in the presence of DCC and using DMSO as a solvent (Scheme 19) (97JCR(S)178). 

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