N-deacetylated derivative

The structure of S10A has been investigated by Baddiley and coworkers.34,35 The polysaccharide is composed of D-galactose, 2-ace-tamido-2-deoxy-D-galactose, ribitol, and phosphate in the molar proportions 4 1 1 1. A hexasaccharide and its N-deacetylated derivative were obtained from S10A by treatment first with base and then... 

Chitosan (N-deacetylated derivative of chitin), a naturally abundant mucopolysaccharide and its derivatives containing COSs were prepared by enzymatic and chemical modification. In addition, chitosan and its derivatives showed potent antioxidant activity. Moreover, chemical modification of chitosan can be easily provided with more powerful antioxidative compounds. Considering the above findings, it is expected that chitosan and its derivatives contained COSs wonld be promising candidates as potent antioxidative agents leading to their valuable use in neutracenticals and expand their applications in Biomedicine. 

Chitosan (CS) is the N-deacetylated derivative of chitin which is one of the most abundant biopolymers and a by-product of fishing industry. Besides... 

Tire 2-dimethylamino derivatives 147 were prepared by a three-step reaction pathway that comprised (a) methylation of the 2-acetamido derivative 144 with methyl iodide and sodium hydride to 145, (b) mild acid-catalyzed N-deacetylation of 145 to 146, and (c) further methylation of 146 to the 2-dimethylamino compound 147 (90JMC1230) (Scheme 57). 

Fig. 35.—13C-N.m.r. Spectra of Acetylated Polymer of Neisseria meningitidis Sero-group Y (A), its O-Deacetylated Derivative (B see 33), and the Polysaccharide of Sero-group W-135 (C see 33). (Solvent, D20, pD 7, at 31° chemical shifts are expressed relative to external tetramethylsilane.)...

Aliphatic aldehydes react to form monoalkylidene derivatives only in presence of potassium r-butoxide. A mechanism has been postulated that also explains the observed N-deacetylation during the formation of the product. The essential step in this is the intramolecular N - O acetyl migration in the initially formed aldol. Subsequent protonation and elimination of the acetoxy group lead to the product (Scheme 26). 

If (he carboxylic acid concerned is a protected aspartic acid, an N-linked asparagine results, an observation that suggested that the procedure could be used for the preparation of glycopeptides. Accordingly, coupling of NPG 52 and aspartic acid 53 in acetonitrile solvent yields the N,N-diacyl derivative 54, which can be chemoselectively AT-deacetylated with piperidine in DMF to give asparagine 55 [19] (Scheme 13a). 

Sodium borohydride reduction of (11), followed by acetylation of the product, gave a mixture of four diastereomeric l-acetoxy-6-acetamidoindolizidines (12), which were separated by careful chromatography on alumina. One of these isomers, cis,cis-l-acetoxy-6-acetamidoindolizidine, was identified as ( )-N-acetylslaframine (13). Deacetylation of (13) was achieved by prolonged boiling with hydrazine hydrate. The OAT-deacetyl derivative (14) so produced was converted by means of benzyl chloroformate into N-carboxybenzylslaframine (15), which was acetylated and finally hydrolysed by hydrobromic acid in acetic acid to (+ )-slaframine (9).7... 

The molecular formula of brasiliamide E (108) was determined to be C22H26N2O4. The 13C-NMR spectrum closely resembled to that of 107, except for the absence of one acetyl group, strongly suggesting that 108 was a deacetyl derivative of 107. The position of an acetyl group was inferred from the HMBC spectrum to be at N-l [81]. 

Analogs of 11, synthesized as (a) potential regulators of the biosynthesis, secretion, and function of immunoglobulins, include the N-[l-ethyl N-(benzyloxycarbonyl)]- (25) and N,N-dimethyl-2-(p-toluenesul-fonamido)succinamide (26), 5-hydrantoinacetic acid (27), 2-thio-5-hydantoinacetic acid (28), and 2,5-dioxopiperazine-3-acetic acid (29) derivatives, which were then O-deacetylated with sodium methoxide and (b) potential metabolic inhibitors of cellular-membrane glycoconju-gates, include the 1-N-glycyl derivative. 

The most common amino polysaccharide is chitosan, derived from chitin by N-deacetylation, and the N-deacetylation reaction can be conducted with little degradation of the polysaccharide chain. The depolymerization and sulfation of chitosan by sulfuric acid have been studied. Chitosan has several applications, for example, in the collection and separation of metal ions, and, in admixture with cellulose, for thin-layer, ion-exchange chromatography. - ... 

The most important chitin derivative is chitosan, obtained by its partial deacetylation under alkaline conditions or by enzymatic hydrolysis in the presence of chitin deacetylase. Because of the semicrystalline morphology of chitin, chitosan obtained by a solid-state reaction has a heterogeneous distribution of acetyl groups along the chain. On the other hand when chitin is treated with concentrated aqueous sodium hydroxide, N-deacetylation proceeds smoothly and homogeneously deacetylated samples are obtained [37]. 

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