Carboxylic acid amides with

In contrast to the reaction of benzamide and other carboxylic acid amides with lead tetraacetate, which has been said to proceed via an acyl nitrene intermediate 46>, methanesulphonamide and 2-biphenylsulphon-amide are completely inert towards this reagent 42>. 

The general procedure of treating carboxylic acid amides with alkaline... 

The 36C1 exchanges between gaseous H 36C1 and adducts of carboxylic acid amides with phosphoryl chloride have also been studied291. 

According to Bredereck et al.,17,18 the reaction of carboxylic acid amides with dialkyl sulfates proceeds via the intermediate ambident cation such as (5). In the case of caprolactam, when excess dialkyl sulfate is taken, the A,(9-dialkyl derivative (6) is formed, which with base forms 3 (Scheme 1). 

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-... 

In the reaction of monosubstituted aliphatic carboxylic acid amides with phosgene, the enamine intermediate can be preferentially reacted with phosgene to form the carbamoyl chlorides XI, a valuable group of chemical intermediates ( °). 

The reaction of substituted carboxylic acid amides with a variety of halogenating agents, such as phosphorus pentachloride, phosphorus penta-bromide, thionyl chloride, and carbonyl chloride, produces imidoyl halides or iminium halides, depending upon the structure of the amide. For example, a monosubstituted carboxylic acid amide can react with carbonyl chloride to produce the imidoyl chloride I, or its hydrochloride II, if R is aliphatic. 

The reaction of carboxylic acid amides with phosphorus pentachloride, to yield compounds I and II, was investigated extensively by Wallach and his students in 1876-1882, and later by v. Braun, who utilized this reaction to degrade secondary amines to ammonia. The highly reactive imidoyl chlorides have been used, especially by v. Braun, as synthetic tools to produce a variety of compounds which could not easily be synthesized by other procedures. However, imidoyl chlorides never made the headlines in synthetic organic chemistry, most likely because of the inherent difficulty involved in handling these highly reactive compounds. 

The classical synthesis of imidoyl chlorides involves the reaction of N-substituted carboxylic acid amides with phosphorus pentahalides. Wallach and his students (288-292 1876-1882 investigated this reaction... 

In the reaction of N-substituted carboxylic acid amides with phosphorus pentachloride generally the corresponding free imidoyl chlorides (I) or their hydrochlorides (II) (iminium chlorides) are formed. If the iminium chlorides are obtained initially, dehydrochlorination can be achieved by simply heating or using a stronger base, such as triethylamine, as the hydrogen chloride scavenger. 

In the reaction of N-disubstituted carboxylic acid amides with phosphorus pentachloride the corresponding iminium chlorides are formed, and again partially isomerization occurs in amides with a-hydrogens. For example, the iminium chloride XXIII and the vinylamine XXIV are formed in the reaction of disubstituted acetic acid diethylamides with phosphorus pentachloride ( 7,262 ... 

The reaction of unsubstituted carboxylic acid amides with iminium chlorides affords the corresponding nitriles... 

Retention of ester groups. Equimolar amounts of startg. nitrile and tetrafluorophthalic acid heated at 135° for 4 days in a heavy-walled glass pressure tube product. Y 56%. Work-up is simple since no solvent is required. F.e.s. W.D. Rounds, G.W. Gribble, Tetrahedron Letters 29, 6557-60 (1988) from carboxylic acid amides with tetrachloro-or tetrafluoro-phthalic anhydride s. ibid. 6553-6. 

Hofmann degradation of carboxylic acid amides with loss of 1 G-atom s. 17, 337... 

Aluminum chloride Ketones and carboxylic acid amides with replacement of alkyl groups Anomalous Friedel-Crafts reaction... 

Palladium-carbon/sulfuric acid Reductive N-alkylation of carboxylic acid amides with acetals... 

Amines from carboxylic acid amides with simultaneous formation of hydrocarbons from tosylates... 

Thiazete ring systems have also been proposed as being intermediates in the reaction of guanidines with carbon disulphide and in the reaction of carboxylic acid amides with thionyl chloride and pyridine. ... 

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