Quaternary nitrogen dealkylation

Condensation of indoles with A-alkylquinolones or TV-alkylpyridones yields yellow and orange zeromethine dyes that dye polyacrylonitrile in lightfast shades [99], If the indole nitrogen atom is unsubstituted, intensely colored anhydro bases are formed from the zeromethinecyanine dyes. Dealkylation of the heterocyclic quaternary nitrogen atom also occurs [100],... 

The Sommelet-Hauser rearrangement has rarely been used as a tool in organic synthesis and then only for very special systems [54], The reason is undoubtedly that the Hofmann elimination and the dealkylation reaction of quaternary nitrogen atoms are in direct competition with the ring expansion reactions of these substrates. 

The phosphorylation of the serine hydroxyl group of cholinesterase by organophosphorus compounds inhibits the activity of this enzyme [192]. This phosphorylation is reversible when the phosphoryl ester so formed is of the dialkoxy type, but becomes irreversible when dealkylation takes place. Wilson [15] found nycleophilic attack of the dialkyl phosphorylated enzyme with hydroxylamine to result in regeneration of the enzyme activity. It has been suggested that some oximes act initially by forming a complex with the phosphorylated enzyme [193-195]. Later work [196] showed the incorporation of a quaternary nitrogen into the nucleophilic molecule (for example A-methylpyridinium-2-aldoxime salts 2-PAM P-2-S prali-... 

Phosphines behave similarly, and compounds of the type R3P and R4P X can be so prepared. The reaction between triphenylphosphine and quaternary salts of nitrogen heterocycles in an aprotic solvent is probably the best way of dealkylating the heterocycles, for example, ... 

Quaternary fluorinated alkyl ammonium compounds The fluorine-containing cationic surfactants of quat type with the general formula C F2 , 1-S02-NH-CH2-CH2-CH2-N (CH3)3 X (n = 8) (Fig. 2.12.1(d)) were examined by FIA—MS using APCI and ESI in the positive and negative modes. The APCI(- -/—) ionisation resulted in a dealkylation at the nitrogen with ions at m/z 585 or 583, respectively. The alkyl chain of this compound contained the moiety C8Fi7. The ions generated under APCI conditions were characterised as dealkylation products—m/z 585 [M — CH2]+ or m/z 583 [M — H— CH3] —as reported in the literature [35,37]. 

Cyclization of haloamines (cyclic amines) dealkylation of quaternary salts of nitrogen heterocycles 0-45 Reaction between dihalides and cy-anamide (cyclic amines)... 

If the heterocyclic base contains several pyridine-type nitrogens select can also be observed. Indeno[l,2-b]quinoxalines, for example, are quaternized at the N-10 atom.110 The alkylation of heterocycles conta one pyrrole-type nitrogen and several pyridine-type nitrogens is appar selective (e.g., indolo[2,3-b]quinoxaline).201 The yields of quaternary however, are extremely low,201 even if phenacyl halides or a-halo ester used.207 Perhaps the resultant quaternary salts are dealkylated.200,207... 

The dealkylation of quaternary ammonium salts by 1,4-diazabicyclo [2,2,23-octane has been described. Electrochemically generated cobalt(i) species catal3rtically cleav carbon-nitrogen bonds in quaternary ammonium salts. 

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