Amino esters ester amides

Cyclization of a-Halo- and a-Sulfonyloxy- l-amino Esters and Amides... 

Potentiometric enzyme-based electrodes have found application in clinical, pharmaceutical, food and biochemical analyses to enable the selective determination of a wide range of important enzyme substrates, including amino acids, esters, amides, acylcholines, /Mactam antibiotics, sugars, enantioselective drugs and many others [74]. 

Dynamic Kinetic Resolution Synthesis of a Fluorinated Amino Acid Ester Amide by a Continuous Process Lipase-mediated Ethanolysis of an Azalactone... 

DKR Synthesis of a FluorinatecI Amino Acid Ester Amide 163... 

Many more recent stoichiometric studies of cobalt(III) complexes have been responsible for most of the developments in this area of research. Cobalt(III) ammine complexes effect hydrolysis of ethyl glycinate in basic conditions via intramolecular attack of a coordinated amide ion hydrolysis by external hydroxide ion attack also occurs (equation 74).341 Replacement of ammonia ligands by a quadridentate or two bidentate ligands allows the formation of aquo-hydroxo complexes and enables intramolecular hydroxide ion attack on a coordinated amino ester, amino amide... 

THE HYDROLYSIS OF AMINO ACID ESTERS, AMIDES AND PEPTIDES 414... 

In addition to the large volume of literature dealing with the metal ion-promoted hydrolysis of a-amino acid esters, amides and peptides a considerable amount of work has been reported on other esters and amides. These developments are considered in the present section. 

Amino acid esters, amides, and peptides can be hydrolyzed in basic solution, and the addition of many different metal ions speeds the reactions. Labile complexes of Cu(II), Co(ll), Ni(II), Mn(II), Ca(II), and Mg(II), as well as other metal ions, promote the reactions. Whether the mechanism is through bidentate coordination of the a-amino group and the carbonyl, or only through the amine, is uncertain, but seems to depend on the... 

Reaction 3, the intramolecular counterpart of reaction 2, has been observed for amino acid esters, amides and nitriles, where five- and six-membered chelate rings can be formed. In the case of the aminoacetonitrile complex (37) a rate enhancement of ca. 10 occurs at pH 7, and this may be compared with an acceleration of ca. 10 for the reaction 1 analogue. For reaction 3, AH values become of considerable significance. 

A wide variety of functional groups such as hydroxy and amino groups, esters, amides, carbamates, acetals, thioacetals, and isolated double bonds are tolerated. Sulfonamides, which are labile towards other reductive reagents such as Na/Hg,144 are unreactive.145 On the other hand, Al/Hg reduces aromatic nitro compounds to the corresponding anilines, a feature that has been used in the... 

Aminolysis with amino acid ester - Amide... 

Amino acid esters, amides, and peptides can be hydrolyzed in basic solution, and metal ions (Cu(II), Co(II), Ni(II), Mn(II), Ca(II), and Mg(II), and others) speed these reactions. The uncertain mechanism is either through bidentate coordination of the a-amino group and the carbonyl, or only through the amine. The rates of these reactions often exhibit complicated temperature dependence and deduction of the mechanism is difficult. Co(III) complexes promote similar reactions. When four of the six octahedral positions are occupied by amine ligands, and two cis positions are available for ligand substitution, these hydrolysis reactions can be examined in detail. These compounds generally catalyze the hydrolysis of N-terminal amino acids from peptides the amino acid that is removed remains bound to the metal. The reactions apparently proceed by coordination of the free amine to cobalt, followed either by coordination of the carbonyl to cobalt and snbseqnent reaction with OFI or H2O (path 1 in Figure 12.16) or reaction of the carbonyl... 

Kim and coworkers have reported a synthetic route to diverse heterocyclic compounds through the nucleophihc addition of P-amino carbonyl compounds 79 to 3-halo-4-methoxybenzynes 78 (Scheme 12.25) [51]. The benzyne intermediate 78 was generated from 5-(3-halo-4-methoxyphenyl)thianthrenium perchlorates 77 upon treatment with lithium diisopropylamide (LDA) in THF at reflux. P-Amino carbonyl compounds, such as P-amino ketones, esters, amides and aldehydes, all react smoothly with benzyne 78 under the reported reaction conditions. Moreover, bis(2-aminophenyl) disulfide, 2-aminophenyl benzenesulfonate... 

In contrast to the above-mentioned amino acid resolution methods involving amino acid esters, -amides, or Af-acylamino acids where the natural L-enantiomer is preferably hydrolyzed from a racemic mixture, hydantoinases usually convert the opposite D-enantiomer [153-155], and L-hydantoinases are known to a lesser extent... 

These photogenerated intermediates can be used in a variety of organic syntheses. Thus, photolysis in the presence of imines gives jff-lactams with high stereoselectivity. Other reactions include the conversion of monoolefins to cyclobutanones " and the synthesis of a-amino esters from amides. These transformations are... 

One of the standard methods for preparing enantiomerically pure compounds is the enantioselective hydrogenation of olefins, a,/3-unsaturated amino acids (esters, amides), a,/3-unsaturated carboxylic acid esters, enol esters, enamides, /3- and y-keto esters etc. catalyzed by chiral cationic rhodium, ruthenium and iridium complexes ". In isotope chemistry, it has only been exploited for the synthesis of e.p. natural and nonnatural H-, C-, C-, and F-labeled a-amino acids and small peptides from TV-protected a-(acylamino)acrylates or cinnamates and unsaturated peptides, respectively (Figure 11.9). This methodology has seen only hmited use, perhaps because of perceived radiation safety issues with the use of hydrogenation procedures on radioactive substrates. Also, versatile alternatives are available, including enantioselective metal hydride/tritide reductions, chiral auxiliary-controlled and biochemical procedures (see this chapter. Sections 11.2.2 and 11.3 and Chapter 12). 

Shemyakin has made a comprehensive study of nucleophilic reactions of 4-halooxazolinones (53) with a variety of alcohols, amines and mercaptans 100, see also 316). Nucleophilic exchange is frequently accompanied by opening of the oxazolinone ring and formation of substituted a-amino acid esters, amides or thiolesters (54). 

Aqueous ammonia and acryUc esters give tertiary amino esters, which form the corresponding amide upon ammonolysis (34). Modem methods of molecular quantum modelling have been appHed to the reaction pathway and energetics for several nucleophiles in these Michael additions (35,36). 

A variety of a-amino acid derivatives, including the acids themselves, haUdes, esters, and amides can be transformed iato hydantoias by coadeasatioa with urea (67). a-Hydroxy acids and thek nitriles give a similar reaction (68) ... 

Aluminum chloride [7446-70-0] is a useful catalyst in the reaction of aromatic amines with ethyleneknine (76). SoHd catalysts promote the reaction of ethyleneknine with ammonia in the gas phase to give ethylenediamine (77). Not only ammonia and amines, but also hydrazine [302-01-2] (78), hydrazoic acid [7782-79-8] (79—82), alkyl azidoformates (83), and acid amides, eg, sulfonamides (84) or 2,4-dioxopyrimidines (85), have been used as ring-opening reagents for ethyleneknine with nitrogen being the nucleophilic center (1). The 2-oxopiperazine skeleton has been synthesized from a-amino acid esters and ethyleneknine (86—89). 

This vinylogous amide has been prepared in 70% yield to protect amino acid esters. It is cleaved by treatment with either aqueous bromine or nitrous acid (90% yield). ... 

The most common O- and N-acylation procedures use acylating agents that are more reactive than caiboxylic acids or their esters. Carboxylic acid chlorides and anhydrides react rapidly with most unhindered hydroxy and amino groups to give esters and amides, respectively ... 

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