Alkyl quaternaries

Thiadiazoles are quaternized to give 3- or mixtures of 2- and 3-alkyl quaternary salts. In 5-amino-1,2,4-thiadiazole, quaternization takes place at the 4-position (90) (64AHC(3il). 1-Substituted 1,2,4-triazoles are quaternized in the 4-position (91), and 4-substituted 1.2,4-triazoles are quaternized in the 1- or the 2-position (92) 64AHC(3)l). 

A strongly basic polystyrene alkyl quaternary amine (hydroxide form) of medium porosity was employed. Research-grade Rexyn... 

Introduction of an alkyl group to the C-13 position of protoberberine was simply accomplished by the reaction of dihydroprotoberberines (230-232) or their 8-acetonyl derivatives (233,234) with alkyl halides, though yields are not always satisfactory. In some cases, oxidized products, protoberberines, and/or Af-alkyl quaternary bases were concomitantly produced. 

The phenomenology described in the preceding section is general since it has been reproduced using different ionic surfactants, such as alkyl sulfonates or alkyl quaternary ammonia [11,12,16]. Villa et al. [17] have also investigated coalescence phenomena in W/OAV globules. They developed a capillary microscopy technique... 

Layers of silicate-bearing hectorites were expanded by the intercalation of the lengthwise alkyl quaternary ammonium cation and simultaneously the interlayer anisotropic silicates stood normally to the layer. 

The reaction of alkyl quaternary salts of pyridine and its benzo analogues with cyanide ion and subsequent loss of the alkyl substituent is known as the Reissert-Kaufmann reaction (Scheme 112). It is not of as much importance for heterocyclic cyanations or alkylations as the other reactions described in this section, chiefly because the N- substituent is such a poor leaving group. 

Tetsuaki Tanaka of Osaka University has reported (Tetrahedron Lett. 45 75, 2004) what appears to be a general route to alkylated quaternary centers, based on the Ti-mediated addition of allylmagnesium chloride to the Sharpless-derived epoxy ether 4. Remarkably, the conversion of 6 to 7 works equally well. 

Carbon-carbon ternary centers can also be assembled by nucleophilic addition. Manfred Braun of the Universitat Diisseldorf has devised (Angew. Chem. bit. Ed. 2004,43,514) the Lewis acidic Ti complex 8. Exposure of a racemic benzylic silyl ether such as 7 to allyltrimethylsilane in the presence of the catalyst 8 leads to the alkylated product 9. Racemic tertiary benzylic ethers are also converted to the alkylated quaternary centers in > 90% . 

Dioxo-l,4,7,10-tetrahydro-l,10-phenanthroline (72) with dimethyl sulfate gives l,4-dihydro-7-methoxy-l-methyl-4-oxo- 1,10-phenanthroline (73) rather than a quaternary salt, steric hindrance presumably preventing alkylation of both nitrogens.203 A related alkylation has also been reported.295 1,2,3,4-Tetrahydro-1,10-phenanthrolines similarly form 1-alkyl derivatives rather than 10-alkyl quaternary salts with alkyl halides.38 The rate of methylation of 1,10-phenanthroline with methyl iodide in dimethyl sulfoxide has been studied,296 and the polaro-graphic reduction of 1 -methyl- 1,10-phenanthrolinium iodide was reported.286... 

Additions to /V-alkeny I imidazoles are influenced by conjugation with the heteroring (Equation 9) a vinyl group is not cleaved when l-vinyl-3-alkyl quaternary salts are thermolyzed and 1-vinylimidazole is not subject to thermal rearrangement (80AHC(27)24t, 82CHEH90,84JHC133). 

Whereas the reaction of the linearly fused 117/-pyrido[2,l -h]quina-zolin-ll-one (27) with alkylating agents (dimethyl sulfate at 120°C, and tri-ethyloxonium tetrafluoroborate in methylene chloride at 20°C) gave exclusively 7V(5)-alkylated quaternary salts (107), that of the isomeric angularly fused 6//-pyrido[l,2-a]quinazolin-6-one (28) with the soft methyl iodide afforded only the iV(5)-methyl quaternary iodide (108, X = I). The reactions of 28 with the hard dimethyl sulfate and triethyloxonium tetrafluoroborate yielded a mixture of 5-methyl-6-oxo-6//-pyrido[l,2-a]quinazolinium salts (108) and 6-alkoxypyrido[l,2-a]quinazolinium salts (109) (90JHC2005). 

A final potential for these fluoroalkyl-functional silanes that must be mentioned is as bound antimicrobial agents. The use of alkyl quaternary ammonium silanes in this application is well known Plueddemann and Revis [25] have claimed fluoroalkyl-containing versions of these organosilicon quaternary ammonium antimicrobial compounds. 

For abbreviation of analyte names see Sect. Abbreviations , log P logarithm of octanol/water partition coefficient n.c. not calculable as N-atom of tropane moiety is present as alkylated quaternary amine, pKb negative decadal logarithm of base constant, SMILES simplified molecular input line entry system... 

When a low foaming cleaner is desired, inclusion of alkoxylated mono alkyl quaternary salts is useful. Such quaternaries, containing both ethoxyl and propoxyl moieties, are effective [75]. 

With two nitrile groups, the delocalized anion is so stable that even a weak, neutral amine (tri-ethylamine) is sufficiently basic to deprotonate the starting material. Here double alkylation again takes place note that the electrophile is good at Sn2, and the solvent is dipolar and aprotic (DMSO and DMF have similar properties). The doubly alkylated quaternary product was formed in 100% yield. 

The heterocyclic alkyl quaternary salts used for preparing spiropyrans are usually obtained by N-alkylating the heterocyclic bases by standard methods. The common bases having an active methyl group of the indolenine, benzothiazole, benzoxazole, and quinoline series some of their substitution products, and a few of their quaternary salts are commercially available. The pyrylium, thiopyrylium, 2-azaazulenium and bcnz[c,d]indolenium salts needed for potentially infrared-absorbing spiropyrans are not (as of the time of writing). 

The divalent metal ion complexes of 2,2 -dipyridyl and 1,10-phenan-throline derivatives are much more susceptible to pseudobase formation than the corresponding N-alkyl quaternary cations. Thus, pXR+ > 14 for pseudobase formation by the N-methyl monocations of both 2,2 -dipyridyl and 1,10-phenanthroline,46 whereas the Pt2+ complexes of these heterocycles have pKR, values of 9.0 and — 11.5, respectively.361,369 This latter value indicates that Pt(l,10-phenanthroline)i+ is less susceptible to pseudobase formation than the 1,10-phenanthrolinium dications 17 (pKR+ = 9.54) and 18 (pKR+ = 9.17).46... 

On quaternization with alkyl halides, 2-quinolyl-4-quinolyl-methanes yield isocyanines and di-(4-quinolyl)methanes the corresponding cyanines. Quinolylamines give azacyanines in an analogous way. Since cyanine dyestuffs are readily prepared by condensation of the A-alkyl quaternary compounds39,40 of quinolylmethanes and -amines, by reactions analogous to those described in Section II, A, 1, the method of preparation involving alkylation of the parent compounds is of little practical use. 

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