Pyrrole as a Directing Group: Regioselective Pd(II)-Catalyzed Alkylation and Benzylation at the Benzene Core of 2-Phenylpyrroles was written by Wahl, Johannes M.;Poethig, Alexander;Bach, Thorsten. And the article was included in Organic Letters in 2016.Reference of 954-81-4 This article mentions the following:
Pyrrole has been employed for the first time as a directing group in the Pd(II)-catalyzed ortho-functionalization of C(sp2)-H bonds. A variety of substituted 2-phenylpyrroles were successfully methylated, alkylated, or benzylated in the ortho-position of the benzene ring, yielding the resp. 2-substituted pyrrol-2-yl benzenes (36 examples, 51-93% yield). Neither additives nor addnl. ligands were required to perform the reaction, which was routinely conducted with PdBr2 as the catalyst and Li2CO3 as the base. Mechanistically, there is evidence that precoordination of palladium to the pyrrole enables the regioselective ortho-attack. In the experiment, the researchers used many compounds, for example, N-(5-Bromopentyl)phthalimide (cas: 954-81-4Reference of 954-81-4).
N-(5-Bromopentyl)phthalimide (cas: 954-81-4) belongs to organobromine compounds. A variety of minor organobromine compounds are found in nature, but none are biosynthesized or required by mammals. Organobromine compounds have fallen under increased scrutiny for their environmental impact. The principal reactions for organobromides include dehydrobromination, Grignard reactions, reductive coupling, and nucleophilic substitution.Reference of 954-81-4
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary