Benzylic quaternary

Benzylic quaternary ammonium salts, when treated with alkali metal amides, undergo a rearrangement called the Sommelet-Hauser rearrangementSince the product is a benzylic tertiary amine, it can be further alkylated and the product again subjected to the rearrangement. This process can be continued around the ring until an ortho position is blocked. ... 

Benzylic quaternary phosphonium and ammonium salts are dealky-lated by mild heating and/or nucleophilic anions, particularly iodide (9) and thiolate (10), but also hydroxide (11). Most N-benzyl-pyridinium or quaternary aryl ammonium compounds are particularly susceptible (12). Decompositions of this sort have seriously limited the usefulness of solid phase-transfer catalysts derived from (chloromethyl)polystyrene (13, 14). 

Unsymmetrical Pyrrolino Benzyl Quaternary Compounds," United States Patent 4,240,965,... 

T. Takemoto, M. Sodeoka, H. Sasai, M. Shibasaki Catalytic Asymmetric Synthesis of Benzylic Quaternary Carbon Centers. An Efficient Synthesis of (-)-Eptazocine , J. Am. Chem. Soc 1993,115, 8477-8478. 

Wittig rearrangement of benzylic quaternary ammonium salts upon treatment with alkali metal amides via the ammonium ylide intermediates. 

Following the discovery that xylocholine blocked transmission at sympathetic nerve terminals, intensive chemical and biological investigations of related compounds revealed that various benzyl quaternary ammonium salts were potent and selective inhibitors of adrenergic nerve function. A review of compounds of this type has been published by Copp [239]. A -2-Bromobenzyl-A(-ethyl-A. A-dimethylammonium tosylate (LIII) (bretylium) has been studied extensively [237, 258], and suppression of adrenergic nerve function has been demonstrated in numerous test situations in various animal species. 

Rearrangement of benzylic quaternary ammonium salts (Sommelet-Hauser)... 

Miscellaneous Derivatives. Other derivatives of toluene, none of which is estimated to consume more than ca 3000 t (106 gal) of toluene annually, are mono- and dinitrotoluene hydrogenated to amines benzotnchloride and chlorotoluene, both used as dye intermediates / rf-butylbenzoic acid from /m-butyltoluene, used as a resin modifier, dodecyltoluene converted to a benzyl quaternary ammonium salt for use as a germidde and biphenyl, obtained as by-product during demelhylation, used in specialty chemicals. Toluene is also used as a denaturant in specially denatured alcohol (SDA) formulas 2-B and 12-A. 

The trimethine dye (10) was also obtained in slightly greater yield, and since the less activated benzyl quaternary salt (7b) gave only the trimethine compound (in 59% yield), this would not appear to be a practical route to the indolizine. (Ethyl orthoformate and 7a in the presence of piperidine gave 9 in 67% yield). 

In a series of studies, Shibasaki examined the formation of chiral benzylic quaternary centers by using asymmetric intramolecular Heck reactions. The effect of double-bond stereochemistry was examined in the cyclization of aryl Inflates 9.1 and 9.3 (Scheme 8G.9) [22], As is commonly... 

Benzylic quaternary salts react with hot dimethyl sulfoxide (DMSO) to give benzaldehyde. For example, benzylammonium chloride gives 60% benzaldehyde plus 24% benzylmethylamine and 5% benzyldimethylamine. 

Scheme 6-30 Asymmetric Heck cyclizations to form benzylic quaternary centers.

Sommelet-Hauser rearrangement The rearrangement of a benzyl quaternary ammonium salt, C6H5CH2N+R3X-, when treated with an alkali metal amide to give the orthomethylbenzyl tertiary amine, o-CH3C6H4CH2NR2. The tertiary amine may subsequently be alkylated, and the reaction... 

Sommelet-Hauser rearrangement. Rearrangement of benzyl quaternary ammonium salts to orr/to-substituted benzyldialkylamines on treatment with alkali metal amides. 

In the presence of NaNH2 benzylic quaternary ammonium salts generally lead to the Sommelet-Hauser rearrangement (refs. 90, 92-104). An ortho alkylation takes place via an exomethylene intermediate. If the two ortho and ortho positions are methylated, the methylene compounds can be isolated (refs. 92, 93). The first anion formed in this reaction can be trapped at a very low temperature (-80 °C) in an aldol reaction for example (ref. 103). At -30°C the isomerization and the rearrangement occur (Fig. 16). 

There is of course a sound reason for the synthetic challenge morphine contains nearly completely dissonant1 arrangement of carbon atoms, a benzylic quaternary center at C13, and its skeleton is prone to a number of fascinating rearrangements thus limiting the methods by which it might become accessible. 

The Tafel colour reaction has been re-examined ° and a method, of potential value in synthesis, has been developed for the selective debenzylation of N-benzyl quaternary salts this involves the treatment of the salt at 0—5 C with lithium n-propylmercaptide (PrSLi) in HMPA. 

The potential utility of o-nitrobenzyl as a photocleavable nitrogen protecting group for indoles, benzimidazole and 6-chlorouracil has been evaluated. Simple photolyses of the protected molecules at 300 nm afford good yields of the starting materials. Nitrobenzyl-based phosphoramide mustards (94) with various substituents (R, R, R ) have been developed as potential prodrugs for cancer therapy. UV and P NMR spectroscopy showed that the phosphoramide mustard was quickly liberated upon irradiation with mercury arc lamps. 2-Nitro-benzyl quaternary ammonium derivatives of norbutyrylcholine (A,iV-dimethyla-minoethyl butyrate) have been synthesized and assessed as photolabile inhibitors... 

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