Amidation of Esters

This work has been extended to transesterification with secondary alcohols [23], and of phosphonate esters [24], Movassaghi and co-workers have demonstrated that NHCs effectively catalyse the amidation of esters with amino alcohols, although an alternative mechanism involving the NHC acting as a Brpnsted base, resulting in nucleophilic activation of the alcohol for an initial transesterification event, followed by rapid O- to iV-acyl transfer, has been proposed [25, 26],... 

The preformed (BC) method is a one-step process used in this case to introduce high multiplicity of terminal hydroxy groups. The method involves direct coupling of branch cell reagents (i.e. tris(hydroxymethyl)aminomethane (Tris-)) by amidation of ester terminated PAMAM dendrimers. Advancement to the next generation of branch cells occurs in one step. 

Antimony(m) ethoxide (Sb(OEt)3) promotes the intermolecular amidation of esters and carboxylic acids with amines under azeotropic conditions.47,48 When tetramino esters are used, the antimony(in)-templated intramolecular macrolactamization provides macrocyclic spermine alkaloids in good yields (Equation (14)). Under the same... 

Some simple examples exploit the electrochemical amidation of esters with amines in the cathodic compartment. ... 

Niacinamide, U5P. Niacinamide, nicotinamide, nicotinic acid amide, is prepared by the amidation of esters of nicotinic acid or by pa.ssing ammonia gas into nicotinic acid at 320°C. Nicotinamide is a white cry.stalline powder that is odorless, or nearly so, and bitter. One gram is soluble in about I mL of water, I.S mL of alcohol, and about 10 mL of glycerin. Aqueous solutions aie neutral to litmus. For occurrence, action, and uses, see nicotinic acid. Niacinamide has pK values of O.. and 3.35. 

In the previous Section 12.1 the formation of amides from the corresponding nitriles is well addressed. The latter method, the enzyme catalyzed reaction of carboxylic esters or acids with ammonia or amines yielding amides, has only recently been studied in depth. Encouraging results have been described, especially in the field of amidation of esters, a technology now being used by BASF to produce optically pure amines (vide infra). 

It has now been reported that the amidation of esters will be used by BASF in the industrial production of amines. A broad range of amines become available in their optically pure form by kinetic resolution using a lipase from Pseudomonas sp. DSM 8246 in the amidation of methoxyacetic acid ethyl ester (see Scheme 12.2-4)[7L... 

Chemoselective transesterificatim of carbohydrates, the 2-OH of 4,6-0-( of 1,3-naphthalenediol has been obsei only moderate (3-OAc 1-OAc l,3-(OA Amidation of esters. Acrylic ai well as N,(V -diacyldiamines are aci diesters are converted to Al-aminosucc )3-Hydroxy esters give equimolar 1 resolved esters. The former compoui alcohols. Racemic amines, like alcoik lion or (V-alkoxycarbonylation. ... 

Amidation of esters. Acrylic and )3-keto amides, protected dipeptides, as well as iV,iV -diacyldiamines are accessible by the enzymatic method. Succinic diesters are converted to V-aminosuccinimides by hydrazines. 

Amidation of esters. Benzyl acetate is a useful acetyl donor. Succinimide... 

Enzymatic synthesis of fV-acylalanine is possible and has been demonstrated recently. Candida antarctica lipase (CAL) has been widely used for the amidation of esters and amines. Izumi and coworkers [75] prepared a N-lauroyl-3-alanine homologous series in organic media, where the enzymatic amidation of 3-amino-propionitrile and P-alanine ethyl ester reacted with methyl caproate or methyl laurate by immobilized C. antarctica lipase as follows ... 

Other methods of polyamidation such as (a) the amidation of esters by primary amines and (b) amidation of nitriles by primary amines are much less used. 

The amidation of esters and amino alcohols is a less widely investigated area with relatively few literature examples. In 2005, nitrogen-heterocyclic carbenes (NHCs) were reported to be catalytic in this transformation." l,3-Bis(2,4,6-trimethylphenyl)-l,3-dihydro-2i -imidazol-2-ylidene (IMes) was chosen as the most suitable carbene, being readily available, reactive and easy to store. It is required in low catalytic loadings of 5 mol% in THF at 23 °C. These mild conditions are highly desirable so that the reaction is compatible with other functional groups and can potentially be used for enantioselective reactions. Reaction times varied from 1.5-24 hours depending on steric bulk and electrophilicity of the ester. 

C2H4N2O3, NH2CONHCOOH. Unknown in the free state as it breaks down immediately to urea and COi- The NH4, Ba, Ca, K and Na salts are known and are prepared by treating ethyl allophanate with the appropriate hydroxide. The esters with alcohols and phenols are crystalline solids, sparingly soluble in water and alcohol. They are formed by passing cyanic acid into alcohols or a solution of an alcohol or phenol in benzene. The amide of allophanic acid is biuret. Alcohols are sometimes isolated and identified by means of their allophanates. 

Method (1) is most frequently used for aliphatic acid amides, while Methods (2a), (2b) and (zc) are used most frequently for aromatic acid amides. Of the last three methods, the Acid Chloride Method (zb) is the most rapid and certain. The Ester Method (za) is practicable only when the amide is insoluble in water, and even then is often very slow unless the ester itself is appreciabb soluble in the aqueous ammonia solution. 

Reaction of esters and lactones with dimethylaluminium amide TL 1979,4907... 

In 1875, Mulder (43) extended the synthesis reaction of thiohydantoine to the ethyl ester and amide of chloroacetic acid. Claus (44) demonstrated the acidic properties of thiohydantoin and its ability to form metallic salts. 

Arylhydrazones of ethyl ester and amide of 4-phenyIthia2oIyIglyoxalic acid R., N ]i i NNHR, r c COjEt ... 

Treat the sodium salt of diethyl acetamidomalonate with isopropyl bromide Remove the amide and ester functions by hydrolysis in aqueous acid then heat to cause (CH3)2CHC(C02H)2... 

Adiponitrile undergoes the typical nitrile reactions, eg, hydrolysis to adipamide and adipic acid and alcoholysis to substituted amides and esters. The most important industrial reaction is the catalytic hydrogenation to hexamethylenediarnine. A variety of catalysts are used for this reduction including cobalt—nickel (46), cobalt manganese (47), cobalt boride (48), copper cobalt (49), and iron oxide (50), and Raney nickel (51). An extensive review on the hydrogenation of nitriles has been recendy pubUshed (10). 

Polymers based on trimellitic anhydride are widely used in premium electromagnetic wire enamels requiring high temperature performance. Several types of trimellitic anhydride-derived polymers are used as wire enamels poly(amide—imide)s (133), poly(ester—imide)s (134), and poly(amide—imide— ester)s (135). Excellent performance characteristics are imparted by trimellitic anhydride-based polymers for wire enamel requirements of flexibiUty, snap, burnout, scrap resistance, heat shock, and dielectric strength. 

Ch1orocarhony1trime11itic acid 1,2-anhydride [1204-28-0] (9), is used in the preparation of esters and amide—imide polymers. TriaHyl trimellitate [2694-54-4] (10) is used as a cross-linking or co-curing agent for ethylene-derived mbbers and plastics. 

Carboxylic Acid Group. Reactions of the carboxyl group include decarboxylation, reduction to alcohols, and the formation of salts, acyl hahdes, amides, and esters. 

Other Applications. Hydroxylamine-O-sulfonic acid [2950-43-8] h.2is many applications in the area of organic synthesis. The use of this material for organic transformations has been thoroughly reviewed (125,126). The preparation of the acid involves the reaction of hydroxjlamine [5470-11-1] with oleum in the presence of ammonium sulfate [7783-20-2] (127). The acid has found appHcation in the preparation of hydra2ines from amines, aUphatic amines from activated methylene compounds, aromatic amines from activated aromatic compounds, amides from esters, and oximes. It is also an important reagent in reductive deamination and specialty nitrile production. 

Sulfated Acids, Amides, and Esters. Reaction with sulfuric acid may be carried out on fatty acids, alkanolamides, and short-chain esters of fatty acids. The disodium salt of sulfated oleic acid is a textile additive and an effective lime soap dispersant. A typical sulfated alkanolamide stmcture is CiiH23C0NHCH2CH20S03Na. Others include the sulfates of mono and diethanolamides of fatty acids in the detergent range. The presence of... 

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