A Practical Route to Substituted 7-Aminoindoles from Pyrrole-3-carboxaldehydes was written by Outlaw, Victor K.;Townsend, Craig A.. And the article was included in Organic Letters in 2014.Safety of 5-Bromo-1H-pyrrole-3-carbaldehyde This article mentions the following:
Among privileged structures, indoles occupy a central place in medicinal chem. and alkaloid research. Here we report a flexible and efficient conversion of pyrrole-3-carboxaldehydes to substituted 7-amino-5-cyanoindoles. Phosphine addition to fumaronitrile proceeds with prototropic rearrangement of the initially formed zwitterion to the thermodynamically favored phosphonium ylide, which is poised for in situ Wittig olefination. The predominantly E-alkene product positions the allylic nitrile for facile intramol. Houben-Hoesch reaction in the presence of BF3·OEt2. Syntheses of 2,5- and 3,5-disubstituted 7-aminoindoles are illustrated. Addnl., dianion alkylation of the allylic nitrile is demonstrated to furnish, after cyclization, 5,6-disubstituted 7-aminoindoles to further exemplify this scalable and high-yielding method. In the experiment, the researchers used many compounds, for example, 5-Bromo-1H-pyrrole-3-carbaldehyde (cas: 881676-32-0Safety of 5-Bromo-1H-pyrrole-3-carbaldehyde).
5-Bromo-1H-pyrrole-3-carbaldehyde (cas: 881676-32-0) belongs to organobromine compounds. Bromine is more electronegative than carbon (2.9 vs 2.5). Consequently, the carbon in a carbon–bromine bond is electrophilic, i.e. alkyl bromides are alkylating agents. Bromine-containing agents predominate because not only are they more efficient than similar chlorine-containing species, but also the high atomic weight of bromine ensures that it is present in a high mass fraction within most organobromine compounds.Safety of 5-Bromo-1H-pyrrole-3-carbaldehyde
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary