Alkyl bromides, derivatives

Figure 1. Chromatogram showing separation of alkyl bromide derivatives of Reagent III. Conditions as described in the text under "HPLC Separation Conditions."...

Alkyl bromides, on the other hand, undergo halogen-metal exchange via single electron transfer processes, and cyclisations of alkyl bromide-derived organolithiums may proceed with significant contribution from radical pathways.117... 

Quaternary pyridinium polymers can show biological activity when bound to surfaces, e.g., poly(4-vinyl pyridine)-modified glass surfaces which were modified using different alkyl bromide derivatives. Suitable polymers for antibacterial applications not only exhibit antibacterial activity, but also non-toxicity to human cells (i.e., selectivity). 

Differences in solubility of the reactants may for example be utilized as follows. Sodium iodide is much more soluble in acetone than are sodium chloride or sodium bromide. Upon treatment of an alkyl chloride or bromide with sodium iodide in acetone, the newly formed sodium chloride or bromide precipitates from the solution and is thus removed from equilibrium. Alkyl iodides can be conveniently prepared in good yields by this route. Alkyl bromides are more reactive as the corresponding chlorides. Of high reactivity are a-halogen ketones, a-halogen carboxylic acids and their derivatives, as well as allyl and benzyl halides. 

HPLC Separation Conditions. Separations of alkyl bromide and alcohol derivatives were performed using an Altex Ultrasphere Cig S Mio>... 

X 150 mm column. The derivatives of methanol, ethanol, 1-propanol, and 1-butanol were separated using a mobile phase of 65% acetonitrile and 35% water, with a flow rate of 1 siL/min. The derivatives of the alkyl bromides were separated using a linear program from 10% acetonitrile and 90% water to 50% acetonitrile and 50% water in 20 min. The flow rate was 1 siL/min. 

The N-alkylated harmine derivatives were prepared by simple alkylation of harmine anions (generated using sodium hydride) with alkyl halides and bromides. For example, 56 was prepared in 83% yield in this manner, and the N-methyl analog (which had similar antitumor activity to that of 56) was obtained in 80% yield using methyl iodide. 

Compounds 38 and 40, prepared by the method shown in Scheme 7 (Section 10.09.6), undergo ready bromocycliza-tion to give oxazolo-fused derivatives 39 and 41 (Equations 8 and 9) <2005JHC755>. In this case, bromination of the thiophene 2-position precedes bromocyclization. Further elaborations are then possible by displacement of the alkyl bromide <2005JHC763>. 

AICI3 gave 5-cyanopyridopyrazine 93. Reaction of H-5 in 91 (R = R = Ph) with NaH in the presence of iodo-methane or benzyl bromide gave the Reissert compound 92 or the alkylated pyridopyrazine derivative 94 depending upon the nature of R when R = Ph, the product was 94, whereas R = OEt gave 92 <1994JHC819>. 

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