title: Pyrrole as a Directing Group: Regioselective Pd(II)-Catalyzed Alkylation and Benzylation at the Benzene Core of 2-Phenylpyrroles.
abstract: Pyrrole has been employed for the first time as a directing group in the Pd(II)-catalyzed ortho-functionalization of C(sp(2))-H bonds. A variety of substituted 2-phenylpyrroles were successfully methylated, alkylated, or benzylated in the ortho-position of the benzene ring, yielding the respective 2-substituted pyrrol-2-yl benzenes (36 examples, 51-93% yield). Neither additives nor additional 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.
authors: Department Chemie and Catalysis Research Center (CRC), Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany.
authors: Johannes M
authors: JM
authors: Wahl
authors: Department Chemie and Catalysis Research Center (CRC), Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany.
authors: Alexander
authors: A
authors: Pöthig
authors: Department Chemie and Catalysis Research Center (CRC), Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany.
authors: Thorsten
authors: T
authors: Bach