And amide formation

As a catalyst for ester and amide formation from acyl chlorides or anhydrides, 4-(di-methylamino)pyridine has been recommended (DMAP G. Hdfle, 1978). In the presence of this agent highly hindered hydroxyl groups, e.g. of steroids and carbohydrates, are acylated under mild conditions, which is difficult to achieve with other catalysts. 

HCO2H, AC2O, 25°, 1 h, 78-90% yield.The use of formic acetic anhydride for esterification and amide formation has been reviewed. ... 

A related agent, g1 icetanile sodium (42), is made b / a variant of this process. Methyl phenyl acetate is reacted with chlorosulfonic acid to give 38, which itself readily reacts with aminopyrimidine derivative 39 to give sulfonamide Saponification to acid 4 is followed by conversion to the acid chloride and amide formation with 5-chloro-2-methoxyaniline to complete the synthesis of the hypoglycemic agent glicetanile (42). ... 

N-Acetylation (Streptomyces roseo chromogenus) Oxidative deamination to carboxylic acid Aspergillus flavus) 5,5 -Dimerization Streptomyces rimosus, Candida tropicalis) Oxidative deamination to carboxylic acid and amide formation Streptomyces rimosus)... 

The biosynthesis of sulfate esters with the help of phosphoadenosine phosphosulfate (PAPS), the active sulfate , (see p. 110) and amide formation with glycine and glutamine also play a role in conjugation. For example, benzoic acid is conjugated with glycine to form the more soluble and less toxic hippuric acid (N-benzoylglycine see p. 324). 

Esterification and amide formation were performed using standard methods (Scheme 46) <1968T2985>. Ester substituents can be hydrolyzed with aqueous sodium hydroxide in tetrahydrothiazines that are stable toward hydrolysis (Equation 35) <1981CPB1554>. 

In a related vein, one of the benzene rings in dibenzepin (36-7) can be replaced by pyridine. In a one-pot reaction, condensation of the 2-chloronicotinic acid (43-2) with ortho-phenylenediamine (43-1) leads to the lactam (43-3). The order in which the two steps, aromatic displacement and amide formation, take place has not been elucidated. Simple alkylation of the anion from the product with 3-chloro-2-(AA -drmethylamino)propane (43-4) affords the antidepressant agent propizepine (43-5) [43]. 

The behavior of a free terminal carboxyl group appears to parallel that of the amino group more closely. Ester exchange and amide formation have been observed for such groups (Equation 51) (54, 61,74). 

With the (S)-PGA enamine-amide route, sitagliptin was prepared in 65% overall yield from 2,4,5-trifluorophenylacetic acid (9) in 4 chemical steps [18]. Two addi-honal crystallization steps are required for enanhomeric purity upgrade and final salt formation. The (S)-PGA enamine-amide hydrogenahon approach eliminated the ester hydrolysis and amide formation steps of the (S)-PGA enamine-ester route by incorporating the newly developed Meldrum s acid chemistry, which enabled direct amidahon with triazole 3. 

The ketone moiety of unsaturated 5-ketolactones 79 both directs and facilitates the reactivity of diaminopropane toward a Michael reaction at C-3 and amide formation with the lactone carbonyl, yielding 3-substituted diazepinones 80, as shown in Scheme 36 <1996JHC703>. 

M 54] [P 48] The ability of the separation-layer concept to prevent fouling even under severe conditions was demonstrated for two fast precipitating reactions, bisquaternization of 4,4 -bipyridyl and amide formation from acetyl chloride [39], Stable operation for a few hours, and in selected cases longer, was achieved. 

Note The decarboxylation, esterification, and amide formation of such carboxylic acids are represented in these examples. 

The structure of this substance isolated from the somatic specific polysaccharide of M. tuberculosis28 was determined from the facts that the corresponding amide was the enantiomorph of 3,5-dimethyl-L-arabonamide (see below) and that by complete methylation followed by hydrolysis, oxidation and amide formation, 2,3,5-trimethyl-D-arabonam-ide was obtained. 

Thomas JB, Fall MJ, Cooper JB, Burgess JP, Carroll FI, Rapid in-plate generation of benzimidazole libraries and amide formation using EEDQ, Tetrahedron Lett., 38 5099-5102, 1997. 

The photochemistry o oxaziridines has been independently investigated. Regiospecific photorearrangements of spiro-oxazirid-ines derived from 2-methylindan-1-one, 2-methyltetral-1-one and 1-methyltetral-2-one have been reported.The oxaziridines (65), for example, are converted on irradiation in ethanol into the lactams (66). A one-photon pathway resulting in ring cleavage and amide formation has also been observed in the gas-phase irradiation... 

---