Functional derivatives amides

Another electrophile that can interact with the isocyanide-derived amide is an aldehyde. However, an additional carbonyl function cannot be introduced as such into one of the components without interfering with the Ugi process. Thus it is better used in masked form as an acetal (Fig. 9). Starting from amine 49 a series of oxopiperazines 51 has been prepared, also on solid phase [66],... 

We have previously seen how cyclic lactams can be synthesized by installing a protected amine in one of the Ugi or Passerini components, followed by cyclization onto the isocyanide-derived amide, taking advantage of the particular reactivity of convertible isocyanides. The same type of compounds can be accessed through nucleophilic attack of the amine onto an ester moiety, suitably installed as additional function into another component. This strategy has been widely used for the preparation of diketopiperazines 104 (Fig. 22), a typical privileged structure, starting with... 

The chlorinated intermediate 255 is eliminated and cycloadds to Cjq, yielding pyrazo-linofullerenes of the structure 257 (Scheme 4.42). The 4-nitrophenyl-group can be replaced by a 4-methoxyphenyl- or a phenyl substituent. In this reaction various aromatics and substituted aromatics are tolerated as residues R (e.g. furan, ferrocene, pyrazole or benzene and substituted benzene). The nitro group of the nitrophenyl residue can be reduced with Sn-HCl to the aniline derivative, which can be further functionalized by amide coupling with acid chlorides [311]. 

By studying the nucleophilic opening of 2,3-epoxy carboxylic acid derivatives it has been found that the regioselectivity was dependent on the acid function (ester, amide, carboxylate), as well as on the nucleophile [78]. In the examples... 

Amides. Although similar to esters in terms of being a functional derivative of a carboxylic acid, amides, unlike esters, are relatively metabolically stable. In general, amides are stable to acid- and base-catalyzed hydrolysis. This stability is related to the overlapping electron clouds within the amide functionality and the corresponding multiple resonance forms. Amidases are enzymes that can catalyze the hydrolysis of amides. Nevertheless, amides are much more stable than esters. 

Trifluoroacrylonitrile can be epoxidized by oxygen with 1,1,2-trichlorotrifluoroethane (CFC-113) as a solvent under pressure at elevated temperatures in moderate yield (Table 2).77 Substituted peroxybenzoic acids are used for the epoxidation of trifluorovinyl alkenes with attached functionalities such as ester, amide or dimethoxyphosphoryl groups (Table 2).7S Functional derivatives of perfluoro-2-methylprop-2-enoic acid are oxidized to the corresponding epoxy compounds in this reaction.78 In the case of ethyl ester 40, the epoxide 41 is contaminated with the adduct of 3-chloroperoxybenzoic acid to the C = C bond, compound 42, that is formed even at low temperatures.78... 

By this definition, an amide, RCONH2, but not a ketone, RCOCH3, is a functional derivative of a carboxylic acid. Several derivatives of carboxylic acids are given in Table 18-3, and methods for preparation of these derivatives are summarized in Tables 18-6 and 18-7 at the end of the chapter. 

SS -ethylenebis[(R)-cysteine] and SS -ethylenebis[(S)-homocysteine] (L) function as ON-donors in Cu(L — 2H),nH20 (n = 0 or l).197 The CuL2C12 complex of dl-methylsulphonium-methioninate is probably octahedral, whilst the CuL Cl of the derived amide acid may be tetrahedral.196 Tetrahedral CuLC12 complexes of the alkaloid ( —)sparteine and its ( —)a- and (— )P-isosparteine diastereoisomers have been prepared.704-... 

The manufacture of the large variety of polyamides (commonly referred to as nylons) occurs through polycondensation of amino carboxylic acids (or functional derivatives of them, e.g. lactams) and from diamines and dicarboxylic acids. Labeling the amino groups with A and the carboxyl groups with B allows differentiation of the different chemical structures between the two types AB (from amino carboxylic acids) and AA-BB (from diamines and dicarboxylic acids). The number of C atoms in the monomers acts as a code number for the identification of the polyamides. The polycaprolactam manufactured from caprolactam (type AB) is then called polyamide 6 (PA 6). The number of carbon atoms in the diamine is given first for type AA-BB followed by the number of atoms in the dicarboxylic acid, e.g. PA 66 for polyhexamethylenedia-dipic amide from hexamethylenediamine and adipic acid. For copolymers the components are separated by a slash, e.g. PA 66/6 (90 10) is a copolymer composed of 90 parts PA 66 and 10 parts PA 6. 

A functional derivative of penicillin amide is the nitrile (71) [104], the activity of which is even lower. 

Another way of producing a low proton activity at the amalgam surface is to add a suitable polar, aprotic compound to the medium. Suitable compounds include urea and its derivatives, amides, lactams, sulfoxides, and sulfones, such as 1,3-dimethylurea, ethyle-neurea, biuret, formamide, A-methyl formamide, acetamide, 5-butyrolactam, dimethyl sulfoxide, di- -butyl sulfoxide, and dimethyl sulfone [41,42]. Dimethylformamide (DMF) or acetonitrile, besides some of the compounds just mentioned, may be used as solvents [43,44]. One function of the added compound is to establish an aprotic reaction layer at the amalgam surface by selective adsorption of the compound on the amalgam another is to solvate the ion pair (consisting of the radical ion and the cation) in a suitable way. 

The OH of an acid can be replaced by a number pf groups—Cl, OR, NH2 —to yield compounds known as acid chlorides, esters, and amides. These compounds are called functional derivatives of acids they ail contain the acyl group ... 

A carboxylic acid is perhaps more often converted into the acid chloride than into any other of its functional derivatives. From the highly reactive acid chloride there can then be obtained many other kinds of compounds, including esters and amides (Sec. 20.8). 

Closely related to the carboxylic acids and to each other are a number of chemical families known as functional derivatives of carboxylic acids acid chlorideSy anhydrides, amides, and esters. These derivatives are compounds in which the —OH of a carboxyl group has been replaced by —Cl, —OOCR, —NH2, or —OR. ... 

Complex alkenyl-copper and -cuprate derivatives, and also alanates, have been generated with high stereochemical purity, and upon treatment with iV-chloromethyl-iV-methylformamide or iV-chloromethyl-phthalimide provide access to highly functionalized allylic amides (entries 1 and 2, Table 7). Addition to acyliminomalonic esters or acyliminophosphonates provides acylaminomalonates and acylamino-alkylphosphonates in modest yield (entries 3 and 4, Table 7). 

Simple alkyl or aryl esters Alkyl esters containing an amino or amido group, or another functionality (Acyloxy)methyl or (acyloxy)ethyl esters Esters of diacylaminopropan-2-ols N,N-Dialkyl hydroxylamino derivatives Amides of amino acids... 

The carboxyl groups available from oxidation of the diamond surface also represent good anchoring sites for further functionalizations. Derivatives can be obtained by acid-catalyzed esterification as well as by a base-catalyzed formation of amides (Figure 5.41). Employing bifunctional alcohols or amines allows for subsequent grafting steps. In principle, the same compounds can be used here like in the modification of chlorinated nanodiamond with alcohols or amines. 

The weakest bond in a polymer chain determines the overall thermal stability of the polymer molecule. The aliphatic carbon-carbon bond has a relatively low bond energy (see Table 5.1). Oxidation of alkylene groups is also observed during prolonged heating in air. Thus the weak links to be avoided are mostly those present in alkylene, alicyclic, unsaturated, and nonaromatic hydrocarbons. On the other hand, the functions proven to be desirable are aromatic (benzenoid or heterocyclic) ether, sulfone, and some carboxylic acid derivatives (amide, imide, etc.). Aromatic rings in the polymer chain also give intrinsically stiff backbone. 

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