Cyclic quaternary ammonium salts

Ring enlargement of cyclic quaternary ammonium salts (cyclic... 

Ring enlargement of cyclic quaternary ammonium salts (cyclic amines) 8-33 Ring expansion of N-acylaziridines (oxazoles)... 

Cyclizations of alkenic amines and imines using organoiron complexes to generate bicyclic 3-lactams are discussed in Chapter 3.1 of this volume. Examples of heterocyclizations of alkenic NA/-dialkylamine and pyridine derivatives to form cyclic quaternary ammonium salts are cited in the Staninets review.Ic A cyclization of an enol thioether has been used to generate a thiazolidine intermediate used in cephalosporin synthesis (equation 131).262... 

More complex equilibria (Fig. 76), also involving chemical modifications, are shown by the aminomethyl derivatives of a-arylidene-P-ketoesters (207), studied as anticancer drugs - these have been found to be in equilibrium with cyclic quaternary ammonium salts, which in turn are characterized by the presence of kcto-enol equilibrium. 

Dialkylaminoalkylphenothiazines may be prepared replacing the usual condensating agent, sodamide, by an excess of sodium hydroxide. In the case of alkyl or haloalkyl halides the V-substitution of phenothiazine in the presence of sodium hydroxide fails. The formation of intermediate cyclic quaternary ammonium salts (133) from the dialkylaminoalkyl halides was suggested to explain this effect. Quaternary ammonium salts appear to catalyze the condensation of alkyl halides with phenothiazine in the presence of NaOH. ... 

Iverson and Madsen [193] reported a synthetically interesting electroreductive ringopening reaction of cyclic quaternary ammonium salts. The stereochemistry of products is greatly affected by pH ... 

Extensive studies by X-rays, IR-, and NMR-spectroscopy (65, 66, 68) on the stereoisomeric pairs of cyclic quaternary ammonium salts showed a preferable axial approach in the quaternization of the iV-alkyl cam-phidine, 2-methylpyrrolidine, and piperidine series while for tropanes the equatorial approach has been substantiated. The increase of a band takes place in the higher region (885-900 cm i) when the iV-methyl is equatorial while the same change occurs in the lower region (840-885 cm i) when iV-methyl is axial (65). The NMR-spectra of a series of iV-methyl and iV-alkyl nortropanium salts show the signal at 7.10 r for the equatorial position and at 6.97 t for the axial one (66). 

VIII. Ylids from Cyclic Quaternary Ammonium Salts. 349... 

Allylic amine is a less reactive leaving group[7], but the allylic ammonium salts 214 (quaternary ammonium salts) can be used for allylalion(l30,131]. Allylic sulfonium salts are also used for the allylation[130]. The allylic nitrile in the cyclic aminonitrile 215 can be displaced probably via x-allylic complex formation. The possibility of the formation of the dihydropyridinium salts 216 and subsequent conjugate addition are less likelyfl 32],... 

As an over-all conclusion, it can be stated that the assumption of ring-chain tautomerism in the pseudo bases derived from the heterocyclic quaternary ammonium salts is quite unnecessary as an explanation of the formation of two (cyclic and open-chain) types of deriva-... 

Quaternary ammonium salts. Salts of alkyl amines. Alkyl chain substituted cyclic amines Acidic pH range Alkaline pH range... 

In our previous works[8,9] on the synthesis of various 5-membered cyclic carbonate, quaternary ammonium salts such as tetrabutylammonium halides showed excellent catalytic activities in relatively mild reaction conditions, under atmospheric pressure and below 140 U. hi this work, several kinds of quaternary ammonium salts have been used for the transesterification reactions of the ethylaie carbonate with methanol to DMC and ethylene glycol. 

Silica gel-based catalytic systems have been described as efficient promoters for a number of organic reactions.28 Illustrative examples include the oxidative cleavage of double bonds catalyzed by silica-supported KM11O4,29 reaction of epoxides with lithium halides to give /i-halohydrins performed on silica gel,30 selective deprotection of terf-butyldimethylsilyl ethers catalyzed by silica gel-supported phosphomolybdic acid (PMA),31 and synthesis of cyclic carbonates from epoxides and carbon dioxide over silica-supported quaternary ammonium salts.32... 

J.-Q. Wang, D.-L. Kong, J.-Y. Chen, F. Cai, and L.-N. He, Synthesis of cyclic carbonates from epoxides and carbon dioxide over silica-supported quaternary ammonium salts under supercritical conditions, /. Mol. Cat. A Chem., 249 (2006) 143-148. 

Synthesis of 5,6-Dihydro-4H-Oxazines Containing Functionalized Substituents at the C-3 Atom Unlike BENAs, six-membered cyclic nitroso acetals do not form quaternary ammonium salts in the reactions with StX/Nu. ... 

Cyclic carbonates have been prepared in the regiospecific ring-opening of oxiranes by butyrolactones catalysed by the quaternary ammonium salt (Scheme 3.6)... 

Cyclic enones can be oxidatively cleaved by a range of reagents to yield keto acids. As ozonolysis can be quite hazardous for large-scale preparations with the build up of ozonides, the procedure has been modified using quaternary ammonium salts to catalyse the transfer of peroxide anion for a rapid oxidative work-up [32]. Two methods are available but, in the safer procedure (10.7.15.A), there is no effective build-up of the ozonide. 

The only cationic surfactant (Fig. 23) found in any quantity in the environment is ditallow dimethylammonium chloride (DTDMAC), which is mainly the quaternary ammonium salt distearyldimethylammonium chloride (DSDMAC). The organic chemistry and characterization of cationic surfactants has been reported and reviewed [330 - 332 ]. The different types of cationic surfactants are fatty acid amides [333], amidoamine [334], imidazoline [335], petroleum feed stock derived surfactants [336], nitrile-derived surfactants [337], aromatic and cyclic surfactants [338], non-nitrogen containing compounds [339], polymeric cationic surfactants [340], and amine oxides [341]. 

The cathodic reduction of cyclic quaternary ammonium compounds can involve a cleavage at the N atom with ring opening as observed for andiriium salts (Scheme 164) [244]. 

Further data from the polarography and cyclic voltammetry in dimethylformamide are given in Table 5.1 for a series of overall two-electron processes leading to cleavage of a benzyl-heteroatom bond. The first electron transfer step is of the dissociative electron transfer type leading to a benzyl radical. This radical is reduced firrther, at the working potential, to the benzyl carbanion. The carbanion fi om benzyl chlorides, esters, ethers, sulphides, sulphones and quaternary ammonium salts can be trapped by carbon dioxide to form phenylacetic acid [2]. Reac-... 

Carbon dioxide can effectively be added to the epoxide ring of GVE to produce the corresponding cyclic carbonate, OVE. Quaternary ammonium salt catalysts showed good catalytic activity even at atmospheric pressure of carbon dioxide. Since the blends of poly(OVE-co-AN) and SAN showed good miscibility, catalytic fixation of carbon dioxide to polymer blends via cyclic carbonate could be one of choice for the reduction and utilization of the greenhouse gcis. 

Monosulfonation of primary and secondary diols can generally be accomplished under controlled conditions. The selective tosylation of diol (54), followed by reaction with trimethylamine in a sealed tube and ion exchange with Dowex-1 (Cl") resin gave (+)-muscarine chloride (55 Scheme 23). ° Intramolecular alkylation of cyclic amine (56) gave quaternary ammonium salt (57) subsequent hydrogenolysis of the benzyl group in (57) afforded (58 Scheme 23). ... 

One of the two hydrogen atoms of phosphoramidates can be temporarily blocked with a trimethylsilyl group. The sodium salt of diethyl V-(trimethylsilyl)phosphoramidate (102) reacted with alkyl bromides in benzene in the presence of 10 mol % of tetra-n-butylammonium bromide to afford, after desilylation, the corresponding V-alkyl derivatives (103) in 79-95% yields for primary alkyl halides. Secondary alkyl halides gave poor results (Scheme 43). The addition of the quaternary ammonium salt is essential to promote the alkylation reaction. Hexamethyldisilazane and its cyclic analogs can also be utilized in the preparation of amines under moderate conditions (Scheme 43). ... 

This method has been applied to a monomer synthesis (2.20).61 The quaternary ammonium salt is used as a phase transfer catalyst. The potassium iodide converts the starting chloride to a more reactive iodide in situ. The alcohol traps the intermediate isocyanate before it can react with the small amount of water that has to be present. If no methanol is present, the corresponding urea is formed in up to 87% yield. If only 0.3 equivalent of water is used, the product is the iso-cyanurate, the cyclic trimer of the isocyanate. Where n = 1, the isocyanatoethyl methacrylate is a useful monomer now made with phosgene (2.21).62 Dow has patented a route from ethanolamine plus a dialkyl carbonate, followed transesterification to a methacrylate carbamate, which is py-rolyzed to the isocyanate (2.22) in 50% yield.63... 

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