Salts acylammonium

The tertiary amines 303 and the acid chlorides 304 (X = Cl) initially formed acylammonium salts 305, which underwent a von Braun type degradation by an attack of the nucleophilic chloride ion at the allyl system to give allyl chlorides 306/307 and carboxylic acid amide functions. 

The general chemistry of acylpyridinium salts (181) and their role in the nucleophilic catalysis by pyridine of carbonyl substitution reactions have been reviewed and compared with the role of acylammonium salts (182). ... 

Based on an X-ray crystal structure analysis of 54, the authors proposed a transition-state where the conformation of the acylammonium salt generated from 54 would be fixed by an attractive electrostatic interaction between the acyl-oxygen and the imidazoyl-2-proton or a dipole minimization effect (Fig. 14) [177]. 

On the other hand, the H-bond between the sulfonylamino proton of the acylammonium salt and the carbamoyl oxygen preferentially promotes the acylation of the... 

King, J. A., Jr. Nucleophilic versus general base catalysis in carbonyl substitution reactions the influence of acylpyridinium/acylammonium salt formation on the observed reaction rate. Trends in Organic Chemistry QQ7, 6, 67-89. 

Quaternary acylammonium salts from carboxylic acid chlorides... 

The ketens used in cycloadditions with cyclopentenes are frequently generated in situ from an acid chloride and a tertiary amine, and the mechanism of these dehydro-halogenations has been investigated. The results suggested that the keten is formed via an acylammonium salt rather than via an enolate. Either species may be trapped under suitable conditions, indicating a complex series of equilibria. 

The elimination of an acyl chloride by a tertiary amine base has been widely used to generate the ketene component in situ due to its convenience and the ready availability of the starting acyl chlorides. The tertiary amine must be a nucleophilic tertiary amine, and triethylamine is generally used. The tertiary amine forms an intermediate acylammonium salt that undergoes decomposition to the ketene. 

Acetylene dicarboxylate reacts with the DABCO-derived acylammonium salts 80 in the presence of K2CO3 to give 2(5)-substituted furan-3,4-dicarboxylates 81 in a single-step transformation [26] ... 

M.E. Abbasov, B.M. Hudson, D.J. Tantillo, D. Romo, Acylammonium salts as dienophiles in Diels-Alder/lactonization organocascades, J. 

Activation of Acyl Chlorides. In several cases, AgBp4 has been used to increase the reactivity of acyl chlorides towards nucleophiles. For example, A-acylammonium salts were prepared for the first time by the reaction of a tertiary amine and an acyl chloride in the presence of AgBp4 (eq 1 ). ... 

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