Two Novel Thermal Biradical Cyclizations of Enyne-Ketenimines: Theory, Experiment, and Synthetic Potential

Michael Schmittel; Jens-Peter Steffen; Miguel Á Wencesla Ángel; Bernd Engels; Christian Lennartz; Michael Hanrath

doi:10.1002/(SICI)1521-3773(19980619)37:11<1562::AID-ANIE1562>3.0.CO;2-H

Two Novel Thermal Biradical Cyclizations of Enyne-Ketenimines: Theory, Experiment, and Synthetic Potential

Angew Chem Int Ed Engl. 1998 Jun 19;37(11):1562-1564. doi: 10.1002/(SICI)1521-3773(19980619)37:11<1562::AID-ANIE1562>3.0.CO;2-H.

Authors

Michael Schmittel¹, Jens-Peter Steffen¹, Miguel Á Wencesla Ángel¹, Bernd Engels², Christian Lennartz², Michael Hanrath²

Affiliations

¹ Institut für Organische Chemie der Universität, Am Hubland, D-97074 Würzburg (Germany), Fax: (+49) 931-888-4606.
² Institut für Physikalische und Theoretische Chemie der Universität, Wegelerstrasse 12, D-53115 Bonn (Germany), Fax: (+49) 228-73-9066.

Abstract

Both benzocarbazoles and quinolines can be synthesized from enyne ketenimines 1 generated in situ via biradical intermediates (see reaction below). Which of the heterocyclic ring systems is formed depends on the choice of the substituent R¹ at the alkyne terminus.

Keywords: Cycloaromatizations; Diradicals; Enynes; Ketenimines; Quantum-chemical calculations.