title: Efficient and General Aerobic Oxidative Cross-Coupling of THIQs with Organozinc Reagents Catalyzed by CuCl2: Proof of a Radical Intermediate.
abstract: A general new method for the highly concise synthesis of C-1-alkylated tetrahydroisoquinolines (THIQ) is reported. The CuCl2-catalyzed procedure is based on a coupling of nonfunctionalized THIQs with organozinc reagents under aerobic conditions. It proceeds in high yields and is broadly applicable to a wide range of substrates. It relies on a regioselective sp(3) C-H bond activation allowing for an sp(3)-sp(3) bond union under mild reaction conditions in a rapid and effective manner. Mechanistically it involves an iminium ion intermediate that is formed via an organic radical involving a single-electron-transfer process. For the first time for this type of reaction a radical intermediate has been proven by EPR spectroscopy.
authors.affiliation: †Kekulé-Intitute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany.
authors.forename: Tongtong
authors.initials: T
authors.lastname: Wang
authors.affiliation: †Kekulé-Intitute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schrempp
authors.affiliation: ‡Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Berndhäuser
authors.affiliation: ‡Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany.
authors.forename: Olav
authors.initials: O
authors.lastname: Schiemann
authors.affiliation: †Kekulé-Intitute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Menche