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Aliphatic amide bond

Ansamacrolides. Antibiotics ia the ansamacroHde family ate also referred to as ansamycias. They are benzenoid or naphthalenoid aromatic compounds ia which nonadjacent positions are bridged by an aliphatic chain to form a cycHc stmcture. One of the aliphatic—aromatic junctions is always an amide bond. Rifampin is a semisyntheticaHy derived member of this family and has clinical importance. It has selective antibacterial activity and inhibits RNA polymerase. [Pg.474]

Local Anaesthetics. Figure 1 Common structure of local anaesthetics. A lipophilic moiety on the left, an aliphatic spacer containing an ester or amide bond in the middle and an amine group on the right are the typical structural elements for local anaesthetic drugs. [Pg.701]

Aliphatic amides possess more strong a-C—H bonds in comparison with amines. This is the result of the carbonyl group influence on the stabilization of the formed a-amidoalkyl radical formed from amide in the reaction with the peroxyl radical. This influence is not so strong as that of the amine group. The values of the a-C—H bond in a few amides were estimated recently by the IPM method [4] and are given here. [Pg.362]

The CES family of proteins is characterized by the ability to hydrolyze a wide variety of aromatic and aliphatic substrates containing ester, thioester, and amide bonds (Heymann 1980, 1982). Cauxin is a member of the CES family, and is secreted from the proximal straight tubular cells into the urine in a species-, sex-, and age-dependent manner. Therefore, we postulated that cauxin was involved in an enzymatic reaction in cat urine and the products made by the reaction should vary with species, sex, and age. Based on this hypothesis, we searched for physiological substrates and products of cauxin in cat urine and identified 2-amino-7-hydroxy-5,5-dimethyl-4-thiaheptanoic acid, also known as felinine. [Pg.55]

N-Methyl substitution does not seem to influence dramatically the hydrolysis of the amide bond. Indeed, a similar relationship between hydrolysis and chain length has been described for unsubstituted aliphatic amides... [Pg.107]

Like the simple aliphatic secondary amides discussed above, structurally more-complex compounds may also be expected to undergo hydrolysis. However, very few such results are available, implying either that xenobio-tics are relatively stable, or that they have been insufficiently studied. It seems that the former reason is the more likely, since the amide bond, in general, is chemically stable and is metabolized over only a narrow range of structures (see, e.g., the /V-alkyl-substituted amides discussed above). Some of the few reported examples of structurally complex xenobiotics that undergo amide hydrolysis are discussed below. [Pg.108]

S)-[ F]fluoroethylcarazolol 8, 111 subtypes of, 100 Adriamycine (doxorubicine), 589 Agrochemical agents, 215 AIF. See Aluminium monofluoride Aliphatic nucleophilic substitution, 28 Alkenes, as amide bond substitutes, 702-703 Alkenes fluorination, 18 Allyl hydrazines as SSAO inhibitors, 674 Aluminium monofluoride, 534 Alumino-fluoride complexes, 364 Alzheimer s disease (AD)... [Pg.778]

The diacid dichlorides used so far in rotaxane synthesis all have arene building blocks in common. Nevertheless, the initial amide bond formed between the dichloride and one stopper molecule (cf. 54) is thought to be responsible for successful molecular recognition of the semi-axle and the macromonocycle. Consequently olefinic and aliphatic diacid dichlorides 59a-g were subjected to the threading procedure to test the need for arene units (Figure 25). [Pg.193]

The mechanism for photodegradation at short wavelengths is generally believed to be initiated by the photolytic cleavage of the amide bond (eq. 17), which has the lowest bond strength in aliphatic polyamides (220 kj/mol (53 kcal/mol))... [Pg.229]

Nonetheless a few commercially successful noncellulosic membrane materials were developed. Polyamide membranes in particular were developed by several groups. Aliphatic polyamides have low rejections and modest fluxes, but aromatic polyamide membranes were successfully developed by Toray [25], Chemstrad (Monsanto) [26] and Permasep (Du Pont) [27], all in hollow fiber form. These membranes have good seawater salt rejections of up to 99.5 %, but the fluxes are low, in the 1 to 3 gal/ft2 day range. The Permasep membrane, in hollow fine fiber form to overcome the low water permeability problems, was produced under the names B-10 and B-15 for seawater desalination plants until the year 2000. The structure of the Permasep B-15 polymer is shown in Figure 5.7. Polyamide membranes, like interfacial composite membranes, are susceptible to degradation by chlorine because of their amide bonds. [Pg.200]

Enzymes are made from just 20 a-amino acid building blocks (structures and abbreviations are shown in Table 5.1). Each amino acid has a unique side chain, or residue, which can be polar, aliphatic, aromatic, acidic, or basic. The amide bonds (peptide bonds) make up the enzyme s backbone, and the residues determine the ultimate structure and catalytic activity of the enzyme. When the sequence of amino acids (the primary structure) for an enzyme is assembled in vivo, it folds... [Pg.191]

A comparison of aliphatic amides, cyclic amides, cyclic imides and 2,4-dioxopyrimidines (uracils) in their deprotonated and diplatinated form (Scheme 4) reveals an increasing steric shielding of the V-bonded Pt ion (Ptx). With respect to formation of stacked and partially oxidized dinuclear species, it is evident that application of the binding principles seen in the blues of cyclic amides to the uracils and imides allows for tetranuclear species only. On the other hand, the presence of an additional O-donor in the imides and uracils (and likewise the cytosines, vide infra) provides an... [Pg.389]

Based on previous work with sulfur monochloride, a reaction pathway leading to 1,2,5-thiadiazole from sulfur monochloride was postulated. Reactions of sulfur monochloride indicate that the molecule can be polarized as C1SS +—Cl and in several instances compounds containing the chlorodithio group (CISS—) have been isolated. Chlorodithio compounds have also been postulated as intermediates in the reaction of aliphatic amides with sulfur monochloride leading to bisamidosulfides and in the Herz reaction. It has also been reported that under the conditions of the Herz reaction o-phenylenediamine is converted to 2,1,3-benzothiadiazole and in this case it appears that the intermediate iV -chlorodithio compound is cleaved at the S—S bond by nucleophilic attack by the ortho amino group, Eq. (1). A similar process was proposed for the formation of... [Pg.121]

Cyclosporine is a hydrophobic cyclic peptide of fungal origin and is composed of 11 amino acid residues. The structure of cyclosporine shows that all of the constituent amino acids are aliphatic (Figure 12.15). UV absorbance at 210 nm is due to the amide bonds in the molecule and is consequently not as intense or distinctive as that of many drugs containing aromatic rings. Development of cyclosporine as a pharmaceutical occurred in the 1970s, a period when HPLC/UV, but not LC/MS, methods were... [Pg.174]

The use of ethoxycarbonyl-protected amino acids as well as methoxycarbonyl derivatives for peptide synthesis was reported in 1903 by Fischer, although the protecting groups in related peptide derivatives could not be cleaved without affecting the peptide bonds,f since urethanes derived from aliphatic primary alcohols are about as stable as the amide bond. Thus, this type of carbamate can only be used for reversible protection of amino groups, at least in... [Pg.43]

Under the conditions used in peptide synthesis, unprotected aliphatic hydroxy groups can undergo two types of side reactions they can be acylated or dehydrated, the latter leading to dehydroamino acids. The hydroxy group of serine is a primary alcoholic function and therefore exhibits the highest reactivity. The secondary alcoholic functions of threonine, hydroxyproline, (3-phenylserine, hydroxynorvaline, and hydroxynorleucine, as well as of other noncoded amino acids, are less reactive and thus more suited for use in the unprotected form. The aromatic hydroxy group of tyrosine is more acidic than the ahphatic hydroxy groups nevertheless, it can be acylated to form esters. These are active esters which in turn can react with primary amines to form amide bonds. [Pg.347]

The 13CNMR data show a characteristic carbonyl carbon at 166 ppm, which corresponds to the carbon attached to the nitrogen via an amide bond. The aliphatic carbon signals can be found between 19 47 ppm for the isobutylamides and 11 15 ppm for the 2-methyl-butylamides. The carbon signals associated with the double and triple bonds of the unsaturated chain can be found between 119-136 and 64-77 ppm, respectively. For additional information regarding 13CNMR, see Perry et al. (1997). [Pg.251]

Mechanisms of aliphatic PA photooxidation under light action in the conditions of amide group absorption [4] where studied. These reactions way flow under the action of short-wave light which boundary at the Earth s surface is 290 nm. The main result of investigations was discovery of the role of radical - CONHCHCH - (Ri ), being the precursor of all basic products of alkylamide oxidation, for example, RC O and Pi, formed at primary photochemical process of photodissociation of amide bond according to the reaction ... [Pg.2]

Capsaicin and capsaicinoids undergo Phase I metabolic conversion involving both oxidative and non-oxidative paths. The liver is the major site of this enzymatic activity. Lee and Kumar (1980) demonstrated the conversion of catechol metabolites via hydroxylation of vanil-lyl ring. In rats, dihydrocapsaicin is metabolized to products that are excreted in the urine as glu-curonides (Kawada and Iwai, 1985). The generation of a quinone derivative occurs via O-demethylation at the aromatic ring with concomitant oxidation of the semiquinone and quinone derivatives or via demethylation of the phenoxy radical intermediate of capsaicin. Additionally, the alkyl side chain of capsaicin is also susceptible to oxidative deamination (Wehmeyer et al., 1990). There is evidence that capsaicinoids can undergo aliphatic oxidation (cu-oxidation) (Surh et al, 1995 Reilly et al, 2003) which is a possible detoxification pathway. Non-oxidative pathways are also involved in the bioconversion of capsaicin, e.g. hydrolysis of the acid-amide bond to yield vanillylamine and fatty acyl moieties (Kawada et al, 1984 Kawada and Iwai, 1985 Oi et al, 1992). [Pg.586]


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See also in sourсe #XX -- [ Pg.34 , Pg.35 ]




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