N-Alkyl bromide

Sulfonamides of primary amines are readily deprotonated (pAia 9-11) and can thus be N-alkylated or N-arylated. Because of their high nucleophilicity and low basicity, deprotonated sulfonamides also react smoothly with less reactive electrophiles, such as n-alkyl bromides [136] (Table 8.9). Sulfonamides can also be N-alkylated with aliphatic alcohols under Mitsunobu conditions. Suitable solvents for the N-alkylation of sulfonamides on polystyrene by Mitsunobu reaction are DCM, toluene, and THF. 

A number of diastereoisomeric pairs of quaternary salts of 5-nitro-tetrahydro-l,3-oxazine derivatives (11a and lib) were prepared by the action of n-alkyl bromides or iodides on 5-nitrotetrahydro-1,3-oxazines.61 The products contained at the 3-equatorial position the n-alkyl derived from the alkyl bromide (or iodide), 6a and 6b [Eqs. (4) and (5)]. 

Second-order rate constant for hydrolysis of ethyl iodide by H2O ( ) used as a surrogate for kH2o,sN for DMIH. Rationale for this approach comes from an analogy with the hydrolysis of n-alkyl bromides, since kn20 N for MeBr, EtBr, n-PrBr and n-HexBr all agree within a factor of two at 25°C (see Table V). 

Influence of Nucleophile Structure on Reactivity. The substrate selectivity of the primary n-alkyl bromides toward the various sulfur nucleophiles listed in Tables IV through WI shows little if any dependence on the length of the alkyl chain (see below). Thus, the data in Tables IV through VII may be used to construct the following approximate order of reactivity of sulfur nucleophiles with respect to the displacement of halide from a primary n-alkyl bromide in H20 ... 

In 1977, some Russian chemists made the same compound by a different route. They chose to introduce the Z double bond by hydrogenation of an alkyne over Lindlar s catalyst. To make the alkyne they needed, they took 1-decyne, treated it with LiNH2 to remove the acidic terminal proton, and reacted the anion with an n-alkyl bromide. 

Tellurolates can be easily alkylated and, under suitable conditions, arylated to produce symmetrical and unsymmetrical diorgano tellurium (p. 387) and alkyl aryl tellurium (p.409) compounds. Examples of alkylating agents are primary n-alkyl bromides and iodides, secondary alkyl bromides, dimethyl sulfate, allyl bromides chlorodifluoro-methane , dichloroiodomethane , methyl m-bromoalkanoates 3-halopropanoic... 

Bromides and iodides can also be considered to contain better leaving groups than chlorides but, again, this seems to have no significant effect on the mechanism. A comparison of the data for benzyl bromide and n-alkyl bromides (see Table 5) strongly suggests Su2 solvolysis, as for benzyl chloride. 

Monoalkylation of the carbanion generated from methyl thiomethyl sulfoxide and 1,3-dithiane I-oxide - has been reported (Scheme 74, entry b) but reexamination of both reactions - proved unsatisfactory under conditions similar to those previously described or slightly modified. Neither the stepwise- nor the one-pot dialkylation was successful at 20 C, but the latter reaction was apparently achieved by Schill- by performing it at 50 °C with a slight excess (2.2 equiv.) of n-alkyl bromides in... 

Several papers have dealt with the comparison of conditions required for N- and C-alkylation of the anions of pyrrole and indole. The results from the early 1990s, support the known ob rvations that iV-alkylation is favored by sodium and potassium cations, whereas C-alkylation is promoted by the more strongly coordinating lithium and magnesium cations <90JCS(Pi)iii>. IV-Alkylation is also favored by polar solvents and the use of tosylates rather than iodides. Under phase transfer conditions, the preference for 7V-alkylation in indoles ranges from 1.5 1 for benzyl bromide to 10 1 for benzyl chloride and n-alkyl bromides, over 3-alkylation <90H(31)447>. 

They chose to introduce the Z doubie bond by hydrogenation of an alkyne over anion with an n-alkyl bromide. By stirring the alkyne with Lindlar s catalyst... 

The chloride ion was formed by dissociative electron capture by CCI4 in a Ni ionization source n-alkyl bromide, at a known concentration, was present in the drift region. The traces in Figure 13.4 are ion mobility spectra obtained at three concentrations of methyl bromide. Figure 13.4a shows the CF peak in addition to two small peaks, each marked with an asterisk, that arise from impurities the small... 

The trimethylammonium surfactants were synthesized from the n-alkyl bromides and a double molar amount of a 40% aqueous trimethylammonium bromide solution. The mixture was diluted with ethanol, producing a 10% solution, and heated together for one hour at 60°C. The slightly yellow product was dissolved in ethanol and precipitated with diethyl ether. All other chemical reagents were of analytical quality from E. Merck (Darmstadt, FRG). 

Sote 1. If there is no rise in temperature, a water-bath at 55 or 60°C should be applied. The reaction is slow compared with that with n-alkyl bromides. note 2. At lower temperatures part of the Grignard compound crystallizes out. 

Alkyl Halides and Tiiflates. n-Alkyl bromides and iodides have been trifluoromethylated with TMSCF3 in the presence of a stoichiometric amount of CsF and 15-crown-5 in DME as solvent, whereas the corresponding chlorides were unreactive. Alkyl triflates have also been transformed into CF3-substituted alkanes with TMSCF3 and TMAF. In contrast, aryl triflates experience nucleophilic attack on the sulfur atom to give hypervalent sulfur compounds (eq 21). 

Symmetrical hexacatenars such as the first described phasmids were obtained as follows (Scheme 1) The three-chain derivative 2 was obtained by etherification of ester 1 with three equivalents of the required n-alkyl bromide, followed by saponification and hydrolysis (a). Esterification of acid 2 chloride with p-nitrophenol (b) afforded ni-troester 3, which was reduced to the corresponding aminoesterd (c). Finally, phasmid 5 was obtained by reaction of two equivalents of 4 with terephthaldehyde. 

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