Amino groups acetylation

Antibacterial sulfonamides contain two N-atoms, the sulfonamido (N1) and the para primary amino (N4). The sulfonamido group, in contrast to a carboxamido group, is chemically and metabolically stable. In other words, hydrolytic cleavage of sulfonamides to produce a sulfonic acid and an amine has never been observed. We, therefore, focus our discussion on the primary amino group, acetylation of which is one of the major metabolic pathways for some sulfonamides. Hydrolysis of the N4-acety luted metabolites back to the parent sulfonamide can occur in the liver, kidney, and intestinal tract. The reaction is strongly influenced by the structure of the parent amine e.g., N4-acetylsulfisoxazole (4.121) was deacetylated by intestinal bacteria whereas /V4-acctyIsulI anilamide (4.122) under identical conditions was not [78][79],... 

Amino terminal residue (amino group) acetyl- formyl- glucosyl- amino acyl- pyruvyl- a-ketobutyryl- methyl- glycuronyl- murein 19... 

Under the influence of nitrosylsulfuric acid, 2-amino-5- and -6-bromo-l-methylben-zimidazoles (183) are converted, as a result of self-coupling, into the 2, 5- (184) and 2, 6-(185) azobenzimidazoles. Even the 5,6-dibromo analogues can react in a similar way by loss of one of the bromine atoms (Scheme 94) (72CHE1533). Coupling with diazonium salts of 4-amino- and 2-methyl-4-amino-benzimidazole occurs at C-7, while a protected 4-amino group (acetylated) directs nitration into both the 5- and 7-positions. A 4-fluoro substituent likewise leads to 7-nitration (74CRV279). 

Acetylation of amines, phenols, and thiols. This reagent readily transfers two acetyl groups to amines, phenols, and thiols under mild conditions (25°) with conversion to 1,4-diacetylglycouril. Ahphatic primary amines react most readily in fact, primary amino groups can be selectively acetylated in the presence of a secondary amino group. Acetylation of aromatic amines is slower, but can be catalyzed by an acid (e. g., acetic acid). Phenols are also acetylated, but aminophenols can be selectively N-acetylated. Thiophenols and alkyl thiols are acetylated readily, but alcohols react only slowly, even at elevated temperatures. ... 

In this case, it doesn t matter which azide you start with triphenylphosphine converts them both to the same aziridine. Like epoxides, aziridines open with nucleophiles under acid catalysis, and azide is used again to put in the second amino group by attack at the less hindered end of the aziridine. To get the right amino group acetylated, the amide is formed before the azide is reduced, this time with tributylphosphine. The drug is formulated as a stable phosphate salt by treatment with phosphoric acid. 

Heparitin sulfate, heparan sulfate a monosulfate ester of an acetylated (IV-acetyl) heparin. As isolated from animal tissues (liver), H. s. is probably a mixture of mucopolysaccharides with varying degrees of sulfa-tation or amino group acetylation. 

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

Other substituents which belong with this group have already been discussed. These include phenol, anisole and compounds related to it ( 5.3.4 the only kinetic data for anisole are for nitration at the encounter rate in sulphuric acid, and with acetyl nitrate in acetic anhydride see 2.5 and 5.3.3, respectively), and acetanilide ( 5.3.4). The cations PhSMe2+, PhSeMe2+, and PhaO+ have also been discussed ( 9.1.2). Amino groups are prevented from showing their character ( — 7 +717) in nitration because conditions enforce reaction through the protonated forms ( 9.1.2). 

However, prior protective acetylation of the amino group leads to a good yield of the 5-nitro compound [2-acetamido-4-methyl-5-nitroselenazole, m.p. 185 C (19)j. Similarly. 2-diethylamino-4-methy)-selenazole with nitric acid gives the. 5-nitro derivative [vellow needles, m.p. 93°C (26)],... 

Other Reactions of Phospholipids. The unsaturated fatty acid groups in soybean lecithin can be halogenated. Acetic anhydride combined with the amino group of phosphatidylethanolamine forms acetylated compounds. PhosphoHpids form addition compounds with salts of heavy metals. Phosphatidylethanolamine and phosphatidjhnositol have affinities for calcium and magnesium ions that are related to interaction with their polar groups. 

Conversion of aniline to acetanilide [103-84-4] by reaction with acetic anhydride, is a convenient method for protecting the amino group. The acetyl group can later be removed by acid or base hydrolysis. 

Nitration. Direct nitration of aromatic amines with nitric acid is not a satisfactory method, because the amino group is susceptible to oxidation. The amino group can be protected by acetylation, and the acetylamino derivative is then used in the nitration step. Nitration of acetanilide in sulfuric acid yields the 4-nitro compound that is hydroly2ed to -rutroaruline [100-01-6]. 

In these cases, it is better to protect the carboxyl group. Optimized conditions for A/-acetylation have been studied (78). A/-Acylation can be utilized for protecting the amino group in the reaction of amino acids, for example in peptide synthesis. 

Plant stmctural material is the polysaccharide cellulose, which is a linear P (1 — 4) linked polymer. Some stmctural polysaccharides iacorporate nitrogen iato thek molecular stmcture an example is chitin, the material which comprises the hard exoskeletons of kisects and cmstaceans. Chitki is a cellulose derivative whereki the OH at C-2 is replaced by an acetylated amino group (—NHCOCH ). Microbial polysaccharides, of which the capsular or extracellular (exopolysaccharides) are probably the most important class, show more diversity both ki monomer units and the nature of thek linkages. 

Amino groups are acetylated normally and are converted to hydroxy compounds with nitrous acid. Tlie 2,3-diamino [2,3-f>] derivative gives an imidazolo fused pyridopyrazine with acetic anhydride (75USP3898216). The oxidative removal of hydrazino groups has been used to give ring-unsubstituted derivatives (79JHC305). 

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