Carboxylic acid amid mixed

This procedure describes the use of pseudoephedrine as a chiral auxiliary for the asymmetric alkylation of carboxylic acid amides. In addition to the low cost and availability in bulk of both enantiomeric forms of the chiral auxiliary, pseudoephedrine, a particular advantage of the method is the facility with which the pseudoephedrine amides are formed. In the case of carboxylic acid anhydrides, the acylation reaction occurs rapidly upon mixing with pseudoephedrine. Because pseudoephedrine amides are frequently crystalline materials, the acylation products are often isolated directly by crystallization, as illustrated in the procedure above. 

More recently, these techniques were extended to several carboxylic acid dimers and mixed carboxylic acid-amide complexes16). 

Liao et al. used a carboxylic acid amide functionalised carbene and a phosphane in a mixed NHC/phosphane palladium(II) catalyst [261]. The system shows the usual ligand exchange behaviour meaning that the PPhj ligand can be substituted by PCyj. This made it possible to study the influence of the phosphane ligand on the performance of the catalyst. In the Suzuki-Miyaura reaction between phenylboronic acid and p-chloroacetophenone, the yield changes dramatically. When PCyj is chosen as the phosphane ligand, then quantitative yield is observed (for both the saturated and unsaturated NHC), but in the case of PPhj the yield drops to 8% (unsaturated NHC) or even 4% (saturated NHC). When... 

The addition of alcohols to nitrilium salts gives rise to formation of alkoxymethyleneiminium salts, which react with bases to yield imido esters (231 Scheme 33). - By deprotonation of carboxylic acid amides ambident anions are formed, which can be alkylated in the presence of silver ions to give imido esters, e.g. (232). " Secondary amides react with trifluoroacetic acid anhydride or trifluorosulfonic acid anhydride to give mixed anhydrides of imidic acids (233). ... 

Diacylamines, mixed s. N-Acyl-carboxylic acid amides C-Diacylation, mixed 17,879 suppl. 26 Diacyl disulfides... 

Subst. carboxylic acid amides from mixed diacylamines... 

Inspired by the many hydrolytically-active metallo enzymes encountered in nature, extensive studies have been performed on so-called metallo micelles. These investigations usually focus on mixed micelles of a common surfactant together with a special chelating surfactant that exhibits a high affinity for transition-metal ions. These aggregates can have remarkable catalytic effects on the hydrolysis of activated carboxylic acid esters, phosphate esters and amides. In these reactions the exact role of the metal ion is not clear and may vary from one system to another. However, there are strong indications that the major function of the metal ion is the coordination of hydroxide anion in the Stem region of the micelle where it is in the proximity of the micelle-bound substrate. The first report of catalysis of a hydrolysis reaction by me tall omi cell es stems from 1978. In the years that... 

Triazole has been prepared by the oxidation of substituted 1,2,4-triazoles, by the treatment of urazole with phosphorus pentasulfide, by heating equimolar quantities of formyl-hydrazine and formamide, by removal of the amino function of 4-amino-l,2,4-triazole, by oxidation of l,2,4-triazole-3(5)-thiol with hydrogen peroxide, by decarboxylation of 1,2,4-triazole-3(5)-carboxylic acid, by heating hydrazine salts with form-amide,by rapidly distilling hydrazine hydrate mixed with two molar equivalents of formamide, i by heating N,N -diformyl-hydrazine with excess ammonia in an autoclave at 200° for 24 hours, and by the reaction of 1,3,5-triazine and hydrazine monohydrochloride. ... 

Conversion of the carboxylic acid to the diethyl amide interestingly leads to an agent that exhibits the properties of a respiratory stimulant. One synthesis of this agent starts with the preparation of the mixed anhydride of nicotinic and benzene-sulfonic acid (4). An exchange reaction between the anhydride and diethyl benzenesulfonamide affords nikethemide (5). ... 

The mechanism of amide formation is a source of insight into the properties of carboxylic acids and amines. Initially, we might expect an amine to act as a base and simply accept a proton from the carboxylic acid. Indeed, that does happen, and a quaternary ammonium salt is formed when the reagents are mixed in the absence of a solvent. For example,... 

The phosphinic isocyanates (116) and isothiocyanates (117) react with oxygen, nitrogen, and phosphorus nucleophiles by attack at carbon rather than phosphorus. Phenyl phosphonodichloridate has been recommended as a useful reagent for the activation (presumably by mixed anhydride formation) of carboxylic acids for conversion to amides and hydrazides. ... 

Carboxylic acids can also be activated by the formation of mixed anhydrides with various phosphoric acid derivatives. Diphenyl phosphoryl azide, for example, is an effective reagent for conversion of amines to amides.140 The proposed mechanism involves formation of the acyl azide as a reactive intermediate. 

Another important N-donor group is the amide group. Contrary to the basic amino groups, the more acidic amide functions tend to be deprotonated in the complex and therefore operate as a monoanionic donor. Alkaline conditions promote the deprotonation and subsequent complex formation. The amide group is a very useful component of mixed donor sets, such as N2S2 or N3S, as discussed in the next chapter. Whether a pure amide coordination may occur in M(V) complexes has not yet been proved. Tetrapeptides do form Tc(V) complexes [68], apparently without involvement of the carboxyl group. The N-donor atom provided by Schiflf bases plays only a role in mixed donor sets and will be discussed below. 

A one-pot conversion of carboxylic acids into esters and amide derivatives from alcohols, amines or hydrazines has been reported [53], which involves the initial reaction of the acid with methane- or toluenesulphonyl chloride to yield a mixed anhydride. 

More recent developments in the field of the Pirkle-type CSPs are the mixed r-donor/ r-acceptor phases such as the Whelk-Of and the Whelk-02 phases.The Whelk-Of is useful for the separation of underiva-tized enantiomers from a number of families, including amides, epoxides, esters, ureas, carbamates, ethers, aziridines, phosphonates, aldehydes, ketones, carboxylic acids, alcohols and non-steroidal anti-inflammatory drugs.It has been used for the separation of warfarin, aryl-amides,aryl-epoxides and aryl-sulphoxides. The phase has broader applicability than the original Pirkle phases. The broad versatility observed on this phase compares with the polysaccharide-derived CSPs... 

Oxidation of the aldehyde group in mixed ether (60-2) by means of perchlorate affords the corresponding carboxylic acid. That product is then converted to its acid chloride (60-6) with thionyl chloride. Treatment of this last intermediate with the substituted pyridine (60-7) leads to the corresponding amide and thus pidamilast (60-8) [62]. 

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