Nitrogen stabilization

Step 4 The oxygen protonated carbmolamme loses water to give a nitrogen stabilized carbocation CeHs H... 

Step 5 The nitrogen stabilized carbocation is the conjugate acid of the imine Proton transfer to water gives the imine... 

Electron release from nitrogen stabilizes the carbonyl group of amides and decreases the rate at which nucleophiles attack the carbonyl carbon... 

Amides however tend to cleave in the opposite direction to produce a nitrogen stabilized acyhum ion... 

Amines have odd numbered molecular weights which helps identify them by mass spectrometry Fragmentation tends to be controlled by the formation of a nitrogen stabilized cation... 

For reactions of A-acyliminium ions with alkenes and alkynes one has to distinguish between A-acyliminium ions locked in an s-trans conformation and those which (can) adopt an s-cis conformation. The former type reacts as a (nitrogen stabilized) carbocation with a C —C multiple bond. Although there are some exceptions, the intramolecular reaction of this type is regarded as an anti addition to the 7t-nucleophile, with (nearly) synchronous bond formation, the conformation of the transition state determining the product configuration. 

An endo-Selective Sequential Epoxidation-Oxyallyl Cycloaddition and the First Nitrogen-Stabilized Oxyallyl Cations. 

Epoxidations of chiral allenamides lead to chiral nitrogen-stabilized oxyallyl catioins that undergo highly stereoselective (4 + 3) cycloaddition reactions with electron-rich dienes.6 These are the first examples of epoxidations of allenes, and the first examples of chiral nitrogen-stabilized oxyallyl cations. Further elaboration of the cycloadducts leads to interesting chiral amino alcohols that can be useful as ligands in asymmetric catalysis (Scheme 2). 

Figure 4 Stabilized bromine antimicrobials are produced by eosinophils, a type of mammalian white blood cell. Bacteria are captured by phagocytosis and contained intracellularly within vesicles called phagosomes. Granules release cationic surfactants, lytic enzymes, and eosinophil peroxidase into the phagosome in a process known as degranulation. Eosinophil peroxidase, an enzyme that is structurally similar to the bromoperoxidases found in seaweed (Figure I), selectively catalyzes oxidation of bromide to hypobromite by reducing hydrogen peroxide to water. The hypobromite immediately reacts with nitrogenous stabilizers such as aminoethanesulfonic acid (taurine) to form more effective and less toxic antimicrobial agents.

Intramolecular stabilization via side-chain donor ligands has also been employed in the nitrogen-stabilized... 

This selectivity is not achievable by simple chemical hydrolysis, since the strained P-lactam ring is much more susceptible to nucleophilic attack than the unstrained side-chain amide function. Normally, the electron-donating effect from the lone pair of the adjacent nitrogen stabilizes the carbonyl against nucleophilic attack (see Section 7.9.2) this is not possible with the P-lactam ring because of the geometric restrictions (see Box 3.20). 

Water Nitrogen-stabilized carbocation Hydronium ion IV-Benzylidenemethylamine... 

Schlessinger has shown that the addition of ester enolates to sulfur stabilized acceptors, e.g. ketene di-thioacetal monoxide (151) and methyl a-(methylthio)acrylate (187), is highly efficient for the synthesis of Y-ketoesters.148 Similarly, Ahlbrecht and Seebach have reported that amide and ester enolate additions to nitrogen stabilized acceptors, e.g. nitroalkenes (40) and 2-(/V-methylanilino)acrylonitrile (59 Scheme 72), are highly efficient.149... 

On the other hand, there is no doubt whatsoever that stable, nitrogen-stabilized silylenes are produced from dihalosilanes and alkali metals98. The chemistry of these silylenes is treated in Section VIII.C. 

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