Amide... s. a. Carboxylic acid

Amides s. a. Carboxylic acid amides. Diamides, Sulfonic acid amides... 

Peptides (s. a. Carboxylic acid amides, subst., Peptoids) exchange of a-aminocarboxylic acids, terminal, in - 11, 569s32... 

Now let s draw the forward scheme. Acid catalyzed hydrolysis of the amide gives a carboxylic acid which is then converted to the acid chloride upon treatment with thionyl chloride. Reaction with a hthium friatkoxyaluminum hydride, followed by water, produces the aldehyde. Subsequent treatment of the aldehyde with methylamine under acid-catalyzed conditions (with removal of water) gives the desired imine. 

There has been a study of the mechanism of the activation of carboxylic acids to peptide formation by chloro-s -triazines in combination with tertiary amines. The first step, exemplified in Scheme 2 by the reaction of 2-chloro-4,6-disubstituted-l,3,5-triazines (18) with A -methylmorpholine, is formation of a quaternary triazinylammonium salt (20). Here there is NMR evidence for the formation at —50°C of the intermediate (19), showing that the substitution involves the two-step SnAt mechanism rather than a synchronous pathway. The subsequent reaction of (20) with a carboxylic acid yields the 2-acyloxy derivative (21), which carries an excellent leaving group for the amide-forming step. ... 

The synthesis of cis-1,4 polymers was also tried by e use of monomers with an s-cis conformation. The solid-state photopolymerization of pyridone derivatives, which is a six-membered cyclic diene amide and is a tautomer of 2-hydroxypyridine, was attempted [100]. Pyridones make hydrogen-bonded cocrystals with a carboxylic acid in the crystalline state. Because the cyclic structure fixes its s-cis conformation, if the polymerization proceeds, a cis-2,5 polymer would be obtained. Actually, however, the photopolymerization did not occur, contrary to our expectation, but [4-1-4] photodimerization proceeded when the carbon-to-carbon distance for the dimerization was small (less than 4 A) [101]. A closer stacking distance of the 2-pyridone moieties might be required for the topochemical polymerization of cychc diene monomers. 

Esters arc most commonly prepared by the reaction of a carboxylic acid and an alcohol with Lhc elimination of water. Esters are also formed by a number of other reactions utilizing acid anhydrides, acid chloride s, amides, nitriles, unsaturated hydrocarbons, ethers, aldehydes, ketones, alcohols, and esters (via ester interchange). 

A carboxylic acid of (+) optical rotation was converted to an amide by way of the acyl chloride. The amide in turn was converted to a primary amine of one less carbon atom than the starting carboxylic acid. The primary amine was identified as 2-S-aminobutane. What was the structure and configuration of the (-l-)-carboxylic acid Indicate the reagents you would need to carry out each step in the overall sequence RC02H —> RCOCI----------> RCONH2-------> RNH2. 

This synthesis also gives a small glimpse at the chemistry of heterocyclic compounds. Most active compounds in today s pharmaceuticals or agrochemicals include heterocycles, as well as most vitamins and natural products. The chemistry of heterocycles is thus very important and lectures or textbooks should be consulted.6 Formation of amide bonds also plays a large role in this problem. It was demonstrated that the strong amide bond can be formed from an amine and a carboxylic acid only after the acid has been activated. This can be done by transformation into the carboxylic halide or imidazolide or by application of an activating agent developed for peptide synthesis. 

For example, the functional group represented by FG might be an amine, and the functional group represented by FG might be a carboxylic acid. Formation of an amide bond between the amine of one monomer and the carboxylic acid of the other results in the formation of a dimer. Continuation of this process results in polymer formation. Let s examine some specific examples to better understand how this process works. 

An aldol addition in present-day terminology involves the addition of the a-C atom of a carbonyl compound, a carboxylic acid, a carboxylic ester, or a carboxylic amide to the C=0 double bond of an aldehyde or a ketone. In the past, the term aldol addition was used in a more restricted sense, referring to the addition of the a-C atom of nothing but carbonyl compounds to the C=0 double bond of aldehydes and ketones. The products of aldol additions in today s usage of the term are (i-hydroxy Icarbonyl compounds (aldols), (i-hydroxy carboxylic acids, /3-hydroxycar-boxylic esters, or /3-hydroxycarboxylic amides. 

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