Carboxylic amide, synthesis

S,3R)-Aziridine-2-carboxylic amide 258 (Scheme 3.95) has been used in the synthesis of the cyclic guanidino amino acid, L-epicapreomycidine (260) [145]. Treatment of 258 with saturated ammonia in methanol at 30 °C for 4 days in a pressure bottle resulted in the aziridine ring-opening product, which afforded 259 in 52 % yield after removal of the Cbz protecting group. 

Sauer and coworkers have presented the use of polystyrene-bound carbodiimide for convenient and rapid amide synthesis [124], An equimolar mixture of 1-methy-lindole-3-carboxylate, the requisite amine, and 1-hydroxybenzotriazole (HOBt) in... 

Another synthetic approach towards the synthesis of compound 80 involves prior deprotonation of the carboxylic amide with f-BuLi, which is then followed by reaction with dimethylzinc (Scheme 10). All three compounds have similar structural features, i.e. they are dimers as a result of two O-bridging enolate anions between two lithium atoms. The... 

The application of lipases in synthetic biotransformations encompasses a wide range of solvolytic reactions of the carboxyl group, such as esterification, transesterification (alcoholysis), perhydrolysis, and aminolysis (amide synthesis) [103]. Transesterification and amide synthesis are preferably performed in an anhydrous medium, often in the presence of activated zeolite, to suppress unwanted hydrolytic side reactions. CaLB (which readily tolerates such conditions [104,105]), PsL, and PcL are often used as the biocatalyst [106]. 

Analogous to the use of chiral enoates (see previous section), a, -unsaturated carboxylic amides, prepared from chiral amines, may be utilized in asymmetric 1,4-additions. When Grignard reagents are added to unsaturated amides (21), derived from (-)-ephedrine (20),25 highly optically active fi-sub-stituted alkanoic acids (22 R and R = alkyl or phenyl) are obtained in a variety of cases, after hydrolysis of the initially formed adducts (Scheme 7). This method was used for the synthesis of the antibiotic (-) malyngolide and its stereoisomers.26 Recrystallization of the intermediate (saturated) amide was necess-... 

Activation of the carboxyl group of 13 is followed by an amide synthesis. 

During solid phase synthesis peptides are bound to the solid support by means of the C-terminal carboxyl group. The properties of the anchor group positioned between the growing oligomer and the solid support are crucial for the success of a solid phase synthesis. Usually, specialised linkers are used which provide either peptide carboxylic acids or peptide carboxylic amides upon cleavage [4]. A cleavage mechanism that proceeds by a nucleophilic attack... 

Carboxylic amides or related substrates, substituted with leaving groups at the /3-position, are suitable substrates for the synthesis of azetidin-2-ones. Relatively stable or labile, in situ generated, leaving groups can be applied. Selective activation of 3-hydroxy-2-hydroxymethyl-2-methylpropanamide 388 with P(NMe2)3-KPF6 and subsequent... 

Amide synthesis. The reagent lisa dehydrating agent compatible with water. It mediates the formation of amides from carboxylic acids and amines. 

When alkyl iodides and ROH were irradiated under CO pressure in the presence of a base such as potassium carbonate, good yields of carboxylic acid esters were obtained (Scheme 4-42) [71]. In the absence of a base, no carbonylation took place. The role of photo-irradiation is to initiate this hybrid radical/ionic reaction by effecting the homolysis of an R-I bond. The thermal initiation process involving allyltin and AIBN has also been found to be useful, as demonstrated by two examples of amide synthesis which are shown in Scheme 4-42 [72], The likely mechanism involves (i) radical initiation via either irradiation or thermal initiation, (ii) radical chain propagation, composed of two reversible type radical reactions (carbonylation and iodine atom transfer) and (iii) ionic quenching to shift... 

The synthesis of cyclopropylamines is also conveniently realized through the Hofmann rearrangement of carboxylic amides. Hofmann degradation of cyclopropanecarboxamide gives access to the parent cyclopropylamine (17) in an excellent yield of 82%. ... 

Amide synthesis. Limited amounts (0.35 equivalent) of the borane-dimethyl sulfide or THF complex promote condensation of carboxylic acids and amines. 

Amidation. Synthesis of nylon 66 involves condensation of amine with carboxyl groups in a melt polymerization. The reaction is represented by Reaction 32. 

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