Reaction with ammonium halides

Under the conditions of the Birch reduction, IV-Boc amides such as 60 can be reductively alkylated in high yields, presumably via a dianion intermediate which is protonated by ammonia at C-5 leaving an enolate anion at C-2 <96JOC7664>. Quenching the reaction with alkyl halides or ammonium chloride then affords the 3-pyrrolines 61. 

The nitrogen atom in quinolizidine derivatives behaves as a tertiary amine and hence it can undergo quaternization by reaction with alkyl halides. For instance, berberine derivative 101 was transformed into 102 by treatment with 3-iodopropanol followed by anion exchange. Compound 102 was then transformed into intermediate 103, which was employed as a precursor for the the preparation of bis-ammonium salt 104 (Scheme 10). This compound showed ultrashort curare-like activity in rhesus monkeys <2001JOC3495>. 

Chloro and bromo cyclophosphazenes are generally prepared by the reaction of chloro or bromophosphoranes with ammonium halides [15] (Eq. 2 and Scheme 1). Special methods are also available for the synthesis of chlorocyclophos-phazenes (Scheme 1). In these reactions cyclic oligomers and linear products are formed, and the former compounds are easily separated from the mixture because of their greater solubility in petroleum solvents. Maximization of cyclic... 

Unsymmetrically -substituted borazines can be prepared by the reaction of IV-substituted borazines or h-trihalogeno-N-substituted borazines and the appropriate amount of Grignard reagent (94). Borazines unsymmetrically substituted on nitrogen have been prepared by the reaction of Hthium borohydride and ammonium chloride and alkyl ammonium chlorides (105,106), and by Uthiation of B- trime thylb o r azine followed by reaction with alkyl halides (107). 

There has been a review of die effects of high pressure on the substitution reactions of amines witii haloaromatic compounds, including polyhalobenzenes.17 Nucleophilic substiditions by amines often proceed readily hi dimethyl sulfoxide (DMSO). The pKa values, hi DMSO, have been reported for some ammonium ions derived from amines widely used as nucleophiles in 5nAt reactions.18 Correlations have been established19 between die oxidation potentials and the basicities of some arylamhie and diarylamine anions and die rate constants for dieir reactions with aiyl halides in DMSO. 

Wilkins, C. /. The Reactions of Hexachlorodisilane with Ammonium Halides and Trimethylamine Hydrohalides. J. chem. Soc. [London] 1953, 3409. 

Cyclophosphazenes are conveniently prepared by the reaction of halophosphoranes with ammonium halides,... 

Organotin halides can also be obtained from oxides or hydroxides on reaction with hydrogen halides (or ammonium halides) (equation 61) and from tin-tin bonded species on reaction with halogens (equation 62). 

The nucleophilic character ofdialkyl sulfides is illustrated by their nucleophilic addition reaction with alkyl halides to form the corresponding sulfonium salts (35) (Scheme 13). Asymmetric sulfonium salts (36) have a tetrahedral configuration therefore, like the analogous chiral saturated carbon compounds, they can be resolved into optical enantiomers (see Chapter 6, p. 81). They are, however, generally less optically stable than sulfoxides, but in sulfonium salts the unshared electron pair can hold its configuration at ordinary temperatures, unlike nitrogen in quaternary ammonium salts, enabling their resolution to be achieved. 

Bis(trimethylsilyl) phosphonite. The reaction with ammonium phosphinate gives (MejSiO)2PH, which is reactive toward unactivated alkyl halides and imines. Accordingly, alkylphosphinic acids and a-aminophosphinic acids are more readily accessible. ... 

Quaternary ammonium salts derived from ephedrine have been used as catalysts for the addition of dialkylzinc to carbonyl compounds (Section D.1.3.1.4.) and are useful as phase-transfer catalysts for alkylation of carbonyl compounds17 and reductions18. N-Benzyl-A -methylephedri-nium salts 10 have found varied application they are easily prepared from A -methylephedrine 913 by reaction with benzyl halide in toluene1 or chloroform/methanol (1 1)18 in high yield. Ref 18 also gives the preparation of other ephedrinium and pseudoephedrinium salts. 

Cleavage reactions of various alkyl 4,6-0-alkylidene-2,3-dideoxy-2,3-epimino-hexopyranosides having the D-allo, u-manno, D-ido, and u-galacto configurations have been performed with azide anion, halo acids, and with ammonium halides. 

Cleavage reactions of epimino derivatives of methyl 4,6-0-benzylidene-2,3-epimino-2,3-dideoxy-a-D-allopyranosides with ammonium halides led either to diaxial or diequatorial isomers, or mixtures of both (Table VI). 

This reaction was initially reported by Flood in 1933. It is a synthesis of trialkylsilyl halide involving the treatment of the mixture of di-trialkylsilyl oxide and concentrated sulfuric acid with sodium halide or ammonium halide. The resulting trialkylsilyl halide can be extracted by petroleum ether and then purified via distillation. It was found that when di-trimethylsilyl oxide is mixed with concentrated sulfuric acid, trimethylsilyl sulfate can be isolated as a white crystalline (m.p., Sb-SS C), which forms trimethylsilyl halide when it reacts with ammonium halide. The reaction has been improved by continuous extraction of the reaction mixture with pentane to yield more and purer trialkylsilyl halide and by the addition of ammonium bisulfate to the reaction mixture. ... 

Trimethyl tetrathiophosphate heated 12 hrs. in a closed flask on a water bath with a 28% soln. of trimethylamine in anhydrous acetone tetramethyl-ammonium dimethyl tetrathiophosphate. Y 85%. — The salts produced give mixed esters by reaction with alkyl halides. Also cleavage of trimethyl trithiol-phosphate s. P. Ghabrier and T. N. Thanh, G. r. 261, 2229 (1965). 

Because a T amine is a better nucleophile than a 1° amine, and a 1° amine is a better nucleophile than ammonia, the products of Rxns lA, IB and 1C on the previous page will compete with the starting material for reaction with alkyl halide (e.g., methyl bromide). ITie result is a mixture of all possible products, including the quaternary (4°) ammonium salt shown below. For this reason direct alkylation of an amine is not a synthetically useful option for making primary, secondary or tertiary amines. 

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