Hydrogen attached to nitrogen

The hydrogen attached to nitrogen can be either axial or equatorial and both chair con formations are approximately equal m stability... 

Merck s thienamycin synthesis commences with mono (V-silylation of dibenzyl aspartate (13, Scheme 2), the bis(benzyl) ester of aspartic acid (12). Thus, treatment of a cooled (0°C) solution of 13 in ether with trimethylsilyl chloride and triethylamine, followed by filtration to remove the triethylamine hydrochloride by-product, provides 11. When 11 is exposed to the action of one equivalent of tm-butylmagnesium chloride, the active hydrogen attached to nitrogen is removed, and the resultant anion spontaneously condenses with the electrophilic ester carbonyl four atoms away. After hydrolysis of the reaction mixture with 2 n HC1 saturated with ammonium chloride, enantiomerically pure azetidinone ester 10 is formed in 65-70% yield from 13. Although it is conceivable that... 

The hydrogen attached to nitrogen in sulphonamide is strongly addle due to the presence of strong electron withdrawing sulphonyl group. Hence, it is soluble in alkali. 

According to the mechanism of Eq. 15-23, a hydride ion is transferred directly from a carbon atom in a substrate to the flavin. However, a labeled hydrogen atom transferred to N-5 or N-l would immediately exchange with the medium, rapid exchange being characteristic of hydrogens attached to nitrogen. 

PYRROLE AND RELATED COMPOUNDS. [CAST 09-97-7]. Pyrrole (monoazole, C4H5N or C4H4NH), contains a ring of 1 nitrogen and 4 carbons, with 1 hydrogen attached to nitrogen and to each carbon ... 

Deuterium (D20) exchange causes the chemical shifts at 7.18 and 9.0-10.0 to disappear. These resonances are assigned to three exchangeable hydrogens attached to nitrogen on the imidazole ring and in the side-chain. 

There is a further contrast between the amides of the two kinds of acids. The substituted amide from a primary amine still has a hydrogen attached to nitrogen, and as a result is acidic in the case of a sulfonamide, this acidity is appreciable, and much greater than for the amide of a carboxylic acid. A monosubstituted sulfonamide is less acidic than a carboxylic acid, but about the same as a phenol (Sec. 24.7) it reacts with aqueous hydroxides to form salts. 

The monosubstituted sulfonamide from a primary amine has an acidic hydrogen attached to nitrogen. Reaction with potassium hydroxide converts this amide into a soluble salt which, if the amine contained fewer than eight carbons is at least partly soluble. Acidification of this solution regenerates the insoluble amide. 

Although the 2,5-dihydropyrimidines (124) could be neither isolated nor detected by spectroscopic means, the migration of hydrogen attached to nitrogen in 123 to the adjacent C-2 (124) was demonstrated by irradiating... 

The tertiary amine does not react because there are no hydrogens attached to nitrogen. 

Ans. Tertiary amines have no hydrogen attached to nitrogen. Amidation requires the presence of a hydrogen on the nitrogen. There must be a hydrogen lost from the nitrogen to couple with the OH that is to be lost from the carboxylic acid. 

Primary amines react with benzenesulfonyl chloride to form A/ substituted benzenesulf-onamides. These, in turn, undergo acid-base reactions with the excess potassium hydroxide to form water-soluble potassium salts. (These reactions take place because the hydrogen attached to nitrogen is made addic by the strongly electron-withdrawing — SO2— group.) At this stage our test tube contains a clear solution. Acidification of... 

Other ammonia derivatives containing an —NHj group react with carbonyl compounds similarly to primary amines. Table 9.1 lists some specific examples. Notice that in each of these reactions, the two hydrogens attached to nitrogen and the oxygen of the carbonyl group are eliminated as water. 

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