Amino groups acylation

A substituted acyl amino group can be introduced by reaction of pyridazine 1-oxide with A-phenylbenzonitrilium hexachloroantimonate 3-A-benzoylanilinopyridazine is formed (75JOC41). 

Glycine (Gly or G) (aminoacetic acid, aminoethanoic acid) is a nonpolar, neutral, aliphatic amino acid with the formula HOOCCH(NH2)H. Gly is the simplest amino acid and plays important roles in peptide and protein chains. It does not contain a side chain and can thus fit into secondary structures where larger amino acids cannot. Gly acts as a transmitter in the CNS where it accomplishes several functions. Gly is a precursor of porphyrins. Gly, Pro, aspartate, Ser, and Asn enable reverse turns. The acylated amino group of Gly can accept a second acyl group to give rise to a diacylamide. ... 

The action of nitric acid on diacetylated p-aminophenol yields a dinitro derivative for which four structures are possible. Hydrolysis followed by deamination gives the known 3,5-dinitrophenol, thus proving that substitution occurs ortho to the acylated amino group.141... 

Acyl nitrenes are highly reactive but unfortunately their precursors, acyl azides, are chemically reactive, e.g. they acylate amino groups. While sulfonyl- and alkoxycarbonyl azides are somewhat less reactive than acyla-zides, and the nitrenes derived from them are highly reactive (Lwowski, 1970 and for sulfonyl nitrenes see Abramovitch et al., 1981 and references therein), the azides must be irradiated in the UV, below 300 nm. Phos-phorylnitrenes are the most reactive nitrenes known and will insert into CH bonds in the presence of hydroxyl groups (Breslow et al., 1974). Again, photolysis occurs at ultraviolet wavelengths. 

Proton abstraction by the o-carbonyl group, as before, yields the immonium ion (222), which then interacts preferably with the acyl-amino group rather than the OH group to give the reduced product (223). It is significant that the product in the sealed tube is bright red and rapidly becomes purple on exposure to the atmosphere, presumably because oxidation to the anthraquinone occurs only in air. 

O-Acyltyrosine derivatives bear the disadvantage of being active esters capable of acylating amino groups or other nucleophiles in a particularly efficient manner by intermolecular O—> N transfer (Scheme 9). Due to the reactivity of these phenyl esters, acyl groups such as acetyl or benzoyl, which are commonly used in carbohydrate chemistry, cannot be recommended for the protection of the tyrosine hydroxy group.f l... 

A second approach has been to acylate amino groups in the aminoglycoside molecule. The acylation of kanamycin with L(-)-4-amino-2-hydrox ybutyric acid has led to the synthesis of BB-K8 [222]. This compound, which is extremely active, fails to act as a substrate for any of the aminoglycoside inactivating enzymes produced by Ps. aeruginosa. However, it has recently been shown that BB-K8 is acetylated by a strain of E. coli [111]. 

This selectivity is discussed in terms of the reduced nucleophilicity of the acylated amino group, compared with the other nitrogen atom of the selenourea. In support, the different products obtained from the two reactions of Scheme 8 are cited. 

The AT-hydroxysuccinimide ester of ethyl diazomalonate is one of a number of succinimide esters that have been used selectively to acylate amino groups, e.g., the amino acid of charged tRNAs (see also Table VI) ... 

For NGs consisting of an acylated amino group (as shown in Scheme 3 with amides and urethanes) participation may occur either via the amino nitrogen ( N-attack , simple case, IS) or the carbonyl oxygen ( 0-attack , complex case, ISC). Thus oxazolines 1 or aziridines 2 and oxazolones 3, respectively, are formed. 

Basicity of HAS Secondary and tertiary HAS are relatively basic and may catalyze hydrolysis of some polycondensation polymers, such as polycarbonate. HAS lose their activity if they come into contact with strong acids, and hence cannot be used to stabilize PVC or in formulations which contain halogenated flame retardants. HAS with an acylated amino group (>NCOCH3) has a lower pfCa and can better resist an acidic environment. 

From a chemical standpoint, the azomethine-type isoindolinones 2 and 4 are derivatives of phthalimide, and may also be viewed as acylated exocyclic amidines with the acyl amino group forming a part of the heterocyde. 

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