Aromatic acid amides substituted

Scheme 20.2 Substituted aromatic nitriles as intermediates for aromatic acids, amides, imines, aldehydes and amines. Elaborated from [82a].

Tetrahydroharman, m.p. 179-80°, has been prepared by a number of workers by a modification of this reaction, viz., by the interaction of tryptamine (3-)5-aminoethylindole) with acetaldehyde or paraldehyde and Hahn et al. have obtained a series of derivatives of tetrahydronorharman by the use of other aldehydes and a-ketonic acids under biological conditions of pH and temperature, while Asahina and Osada, by the action of aromatic acid chlorides on the same amine, have prepared a series of amides from which the corresponding substituted dihydronorharmans have been made by effecting ring closure with phosphorus pentoxide in xylene solution. 

Assignments for C—H out-of-plane bending bands in the spectra of substituted benzenes appear in the chart of characteristic group absorptions (Appendix C). These assignments are usually reliable for alkyl-substituted benzenes, but caution must be observed in the interpretation of spectra when polar groups are attached directly to the ring, for example, in nitroben-zenes, aromatic acids, and esters or amides of aromatic acids. 

Substituted aromatic carboxylic acid amides of the type ArCONHR and Ar-CONR2 are only slowly attacked by aqueous alkali and are characterised by hydrolysis under acidic conditions 70 per cent sulphuric acid (prepared by carefully adding 4 parts of acid to 3 parts of water) is the preferred reagent. Use the general procedure which has been outlined on p. 1229 characterise the acidic and basic components. 

In the synthesis of specially substituted methylene diphosphines, made from secondary phosphines and carbonyl derivatives (7), a carbenium ion adjacent to trivalent phosphorus as the transition state has been discussed. The transfer of this reaction principle to primary phosphines and suitable carbonyl compound revealed a further pathway to derivatives of dicoordinated phosphorus (8). Aromatic phosphines react with carboxylic acid amide acetals under elimination of alcohol giving dialkylamino-alkylidene phosphines (Scheme 5). A modification of the synthesis... 

SMP amide enolates have been employed by several research groups. Alkylation of SMP amide enolates gives a-substituted acids (eq 3). Excellent yields and stereoselectivities are observed in the Birch reduction of aromatic SMP amides with subsequent alkylation (eq 4). ... 

Heating of secondary carboxylic acid amides with HMPA gives rise to formation of A(-substituted V JV -dimethylamidines (310 Scheme 48). - In this procedure the secondary amide can be replaced by a ketoxime in which at least one substituent has to be an aromatic one. Similar methods were de-... 

There are a few efficient methods for the stereoselective synthesis of vinyl halides, and this transformation remains a synthetic challenge. Research by S. Roy showed that the Hunsdiecker reaction can be made metal free and catalytic catalytic Hunsdiecker reaction) and can be used to prepare ( )-vinyl halides from aromatic a,p-unsaturated carboxylic acids. The unsaturated aromatic acids were mixed with catalytic amounts of TBATFA and the A/-halo-succinimide was added in portions over time at ambient temperature. The yields are good to excellent even for activated aromatic rings which do not undergo the classical Hunsdiecker reaction. The fastest halodecarboxylation occurs with NBS, but NCS and NIS are considerably slower. The nature of the applied solvents is absolutely critical, and DCE proved to be the best. This strategy was extended and applied in the form of a one-pot tandem Hunsdiecker reaction-Heck coupling to prepare aryl substituted (2 ,4 )-dienoic acids, esters, and amides. 

CHS. CO. ONH< = CHS. CO. NH + H 0 In order to purify the amide thus obtained, the reaction-mixture may be fractionated, as in the case of acetamide, or if the amide separates out in a solid condition, it may be purified by filtering off the impurities and crystallising. Substituted acid-amides, and espedally easily substituted aromatic amides, eg. acetanilide, can also be readily obtained by this method, by heating a mixture of the acid and amine a long time in an open vessel ... 

Combinatorial parallel synthesis of head-to-tail bisbenzimidazoles 41 has been performed using polymer-immobilized 1,2-diaminobenzenes (Fig. 2). The PEG-bound diamines were hf-acylated at the primary aromatic amino group with 4-fluoro-3-nitrobenzoic acid. The substituted amides were cy-clized to benzimidazoles under acidic conditions. Successive reduction and cyclization with various aldehydes yielded 5-(benzimidazol-2-yl)benzimid-azoles. Finally, the desired products 41 were released from the polymer support to afford the bisbenzimidazoles in good yields and with high purity [46]. 

Not only the smallest optically active amino acid, for example alanine, but also valine, leucine, several (substituted) aromatic amino acids, heterosubstituted amino acids (methionine, homomethionine and thienylglycine) and even an imino acid, proline, are obtainable in both the l- and the D-form. Furthermore, this biocatalyst has recently been reported to hydrolyze azido amino acid amides with high enantioselectivities as well (vide infra)[32). 

Microwave irradiation has been employed in several published syntheses of substituted imidazoles. Microwave irradiation of aldehydes 87 and TV-substituted a-amino acid amides 88 under solvent-free conditions led to substituted imidazolidin-4-ones 89 <04H(63)1165>. A simple, high yielding synthesis of 2,4,5-trisubstituted imidazoles 91 have been prepared from diketone 90 with aromatic aldehydes in the presence of excess ammonium acetate in acetic acid under microwave irradiation <04OL1453>. Condensation of benzoin 92, aromatie aldehydes, amines and ammonium acetate in the presence of silica gel under microwave irradiation and solvent-free conditions led to tetrasubstituted imidazoles 93 <04H(63)87>. 

Within the last two decades, a number of chemical structures have been proposed as metal deactivators for polyolefins. These include carboxylic acid amides of aromatic mono- and di-carboxylic acids and N-substituted derivatives such as N,N -diphenyloxamide, cyclic amides such as barbituric acid, hydrazones and bishydrazones of aromatic aldehydes such as benzaldehyde and salicylaldehyde or of o-hydroxy-arylketones, hydrazides of aliphatic and aromatic mono- and di-carboxylic acids as well as N-acylated derivatives thereof, bisacylated hydrazine derivatives, polyhydrazides, and phosphorus acid ester of a thiobisphenol. An index of trade names and suppliers of a few commercial metal deactivators is given in Appendix A4. 

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