Hexahelicenophanes and Their Racemization

Herbert Meier; Manfred Schwertel; Dieter Schollmeyer

doi:10.1002/(SICI)1521-3773(19980817)37:15<2110::AID-ANIE2110>3.0.CO;2-K

Hexahelicenophanes and Their Racemization

Angew Chem Int Ed Engl. 1998 Aug 17;37(15):2110-2113. doi: 10.1002/(SICI)1521-3773(19980817)37:15<2110::AID-ANIE2110>3.0.CO;2-K.

Authors

Herbert Meier¹, Manfred Schwertel¹, Dieter Schollmeyer¹

Affiliation

¹ Institut für Organische Chemie der Universität, J. J. Becherweg 18-22, D-55099 Mainz (Germany), Fax: (+49) 6131-395396.

Abstract

A drastic increase in the rate of racemization is found for the bridged hexahelicenophanes 1 (n=8, 10) relative to the unsubstituted parent [6]helicene. This unexpected result occurs from steric interactions between the polymethylenedioxy chains and the terminal rings, which causes the energy of the ground state to be raised and that of the transition state to be lowered.

Keywords: Cyclophanes; Helical structures; Kinetics; Racemization.