Introduction of amino group

A.mina.tlon. Amination describes the introduction of amino groups into aromatic molecules by reaction of ammonia or an amine with suitably substituted halogeno, hydroxy, or sulfonated derivatives by nucleophilic displacement. Although reaction and operational conditions vary, the process always involves the heating of the appropriate precursor with excess aqueous ammonia or amine under pressure. 

Thiadiazole has an absorption maximum at 229 nm (log e 3.7). The introduction of amino groups into the heteroaromatic nucleus results in a bathochromic shift. Thus, the maximum due to the 1,2,4-thiadiazole ring is moved to 247 nm in 5-amino and to 256nm in 3,5-diamino-l,2,4-thiadiazole <1996CHEG-II(4)307>. No new publications relating to the ultraviolet (UV) spectra of 1,2,4-thiadiazoles have appeared since the publication of CHEC-II(1996). 

Deoxoartemisinin and carboxypropyldeoxoartimisinin have also been shown to have anti-tumour activity and, NMR studies on solution conformations have been reported <00BBR359>. One of the problems with artemisinin use is its poor water solubility characteristics. An attempt to rectify this, and to overcome stability problems associated with sodium artesunate in solution, has involved the introduction of amino group functionality as in 127 (eg. R = 0(CH2)3NR r2 where NR r2 = morpholine). The maleate salt of this compound has reasonable water solubility and aqueous solutions are stable at room temperature for an extended time. However activity against Plasmodium knowlesi in rhesus monkeys after oral administration was poorer compared with artesunic acid <00JMC1635>. 

Introduction of Amino Groups The introduction of an amino (-NH2) group (in ortho position) into a benzene ring already having a nitro (-N02) group is one of the simplest and oldest approaches to enhance thermal stability of explosives [35-37]. This is evident from the study of the effect of introduction of amino groups in trinitrobenzene (TNB) [Structure (2.18)] to form monoamino-2,4,6-... 

The concept of enhancing thermal stability by the introduction of amino groups is further supported by Chinese work [28]. Some typical examples are shown under Schemes 2.2-2.4. 

These examples of explosives show beyond doubt that the m.p. is raised by the introduction of amino group/s. Further, data on thermal decomposition show that the thermal stability is associated with high melting point and low vapor pressure... 

Introduction of amino groups into pteridine lowers the solubility in all solvents despite the fact that the amino group almost invariably increases the solubility in water of aliphatics and aromatics. The reduced solubility of aminopteridines is due to intermolecular hydrogen bonding. 

Transamination reactions on keto sugars allow the introduction of amino groups as seen in the amino sugars glucosamine and galac-tosamine (Figure 8.10). These compounds, as their N-acetyl derivatives, are part of the structures of several natural polysaccharides, and... 

It is possible by modification of reaction conditions to effect the introduction of amino groups into the 2-position of naphthoxidine, but this generally produces dyes with reduced purity of shade and of lower lightfastness [1]. 

Introduction of amino groups Introduction of conjugation Condensation with a triazole ring. 

The introduction of amino groups into phenols and ethers can be accomplished by the formation and reductive cleavage of their azo compounds. The diazotizing agent may be prepared from sulfanilic acid, and the reduction can be performed with sodium hydrosulfite. Excellent examples are found in the synthesis of l-amino-2-naphthol (85%) and 4-amino-l-naphthol (75%). ... 

In nucleotides, azides have been used for the introduction of amino groups into either the purine moiety, as in the synthesis of 8-aminoadenosine , or into the sugar moiety, as in the synthesis of 5-amino-5-deoxy uridine . 

Vicarious nucleophilic substitution (3.3.3) permits the introduction of amino groups para (or ortho if para blocked) to nitro groups by reaction with methoxyamine or 1-amino-l,2,4-triazole. In contrast, VNS substitution of 3-nitropyridine with benzyl chloroacetate proceeds at C-4. °... 

The hydroxyimino group attached to carbon (C=NOH) may be converted into an amino group by way of the intermediate hydroxyamino or imino group. The reduction of oximes can be conducted so as to yield (1) a synthesis of amines from carbonyl compounds, (2) introduction of amino groups into a compound containing active methylene groups (by way of the isonitroso compounds obtained by nitrosation), or (3) production of amines from the adducts of nitrogen oxides or nitrosyl chloride to olefins. 

Vicarious nucleophilic substitution (section 2.3.3) permits the introduction of amino groups ortfto to nitro groups by reaction with methoxyamine as illustrated below. 

It may be seen that enhanced coupling results from both methylation at nitrogen (1.1 Hz) and the introduction of amino group at the para position (2.6 Hz), whereas methylation at the ortho positions causes a small decrease (0.2 Hz). The decrease in 7( N C) of Af,Af-dimethylaniline and its iV,iV-dimethyl derivatives is explained by inhibition of the resonance interaction resulting from stericaUy induced twisting of the substituent group from coplanarity with the aryl ring. 

Probes to be immobilised in the gel pads must be activated in order to contain chemically reactive groups for coupling with the activated gel pads. For example, immobihsation in aldehyde-containing gels would require the probe to be functionahsed by introduction of amino groups [16]. The probe is prepared either... 

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