Of carboxylic acid esters, and

Reduction of Carboxylic Acids, Esters, and Anhydrides to Aldehydes ... 

The chemistry of a-haloketones, a-haloaldehydes and a-haloimines Nitrones, nitronates and nitroxides Crown ethers and analogs Cyclopropane derived reactive intermediates Synthesis of carboxylic acids, esters and their derivatives The silicon-heteroatom bond Syntheses of lactones and lactams The syntheses of sulphones, sulphoxides and cyclic sulphides... 

Before discussmg the mechanism of cleavage of carboxylic acid esters and amides by hydrolases, some chemical principles are worth recalling. The chemical hydrolysis of carboxylic acid derivatives can be catalyzed by acid or base, and, in both cases, the mechanisms involve addition-elimination via a tetrahedral intermediate. A general scheme of ester and amide hydrolysis is presented in Fig. 3. / the chemical mechanisms of ester hydrolysis will be... 

Fig. 3.1. General scheme for chemical hydrolysis of carboxylic acid esters and amides. Pathway a Proton (general acid) catalyzed hydrolysis. Pathway b HO (general base) catalyzed...

Kinetic Enolization of Carboxylic Acid Esters and Amides (Scheme 7)... 

This method is compatible with many functional groups and shows considerable selectivity. Phosphonic acid esters may be cleaved in the presence of carboxylic acid esters, and phosphonate methyl esters are cleaved approximately 25 times faster than the isopropyl esters. For example, the phosphonate methyl ester of the hexapeptide analogue 78 was cleaved with TMSBr to give the aspartic peptidase inhibitor 79 in 64% yield (Scheme 28). 66 ... 

Wolfe. J.F.. and M A. Ogliamso Synthesis of Carboxylic Acids. Esters and Tlreir Derivaihes-Vpdates. John Wiley Sons. Inc.. New York. NY. 1991... 

Lithium aluminum hydride usually reduces carbonyl groups without affecting carbon-carbon double bonds. It is, in addition, a good reducing agent for carbonyl groups of carboxylic acids, esters, and other acid derivatives, as will be described in Chapter 18. 

M. A. Ogliaruso and J. E Wolfe, "Synthesis of Carboxylic Acids, Esters, and Their Derivatives, Eds. S. Patai and Z. Rappoport, J. Wiley Sons, New York (1991)... 

Fig. 13.7. Conformational dependence of the enthalpy of carboxylic acid esters and the conformational dependence of the C,H acidity of carboxylic acid esters based on it.

HYDROGENATION OF CARBOXYLIC ACIDS, ESTERS, AND RELATED COMPOUNDS... 

The synthetic utility of azolides is exemplified by many examples of their use in the synthesis of carboxylic acids, esters, and thioesters, amides and thioamides, aldehydes and ketones, and phosphorylated imidazoles and benzimidazoles. 

Zinc enolate chemistry is rich and was recently reviewed However, it is dominated by species with a-alkoxy groups, i.e. the enolate of carboxylic acid esters, and so these studies are not relevant in the current context. Acetophenone, 2-acetylthiophene and 3-acetylthiophene form enolate complexes with Zn and The degree of... 

The two major techniques for the preparation of triazolecarboxylic acids are the ami-drazone method and transformations or replacements of existing functions. In the former case one can introduce the carboxylic acid through starting materials such as (323). Alternatively, cyclization of other amidrazones can be accomplished with derivatives of oxalic acid, e.g. by converting the acylamidrazone (324) into the amide (325) from which the acid may be liberated by hydrolysis. A particularly convenient method for the preparation of carboxylic acids, esters and amides is the rearrangement arylazooxazolinones (Scheme 117). 

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