Synthesis 2011(6): 905-908  
DOI: 10.1055/s-0030-1258435
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis and Photoisomerization of Diarylcyclobutenes

Peter Rastera, Stefan Weissa, Gerhard Hiltb, Burkhard König*a
a Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
b Fachbereich Chemie, Philipps-Universität Marburg, 35037 Marburg, Germany
Fax: +49(941)9431717; e-Mail: Burkhard.koenig@chemie.uni-regensburg.de;
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Publikationsverlauf

Received 6 January 2011
Publikationsdatum:
11. Februar 2011 (online)

Abstract

Symmetrically and unsymmetrically substituted diarylcyclobutenes are synthesized in 20-70% yields from alkyne precursors via cobalt-catalyzed [2+2] cycloadditions. The reactions proceed under mild conditions and provide access to differently substituted diarylethene derivatives. All the diarylcyclobutene products undergo reversible photoisomerization upon irradiation with UV/Vis light. The ring-closed isomers show different thermal stabilities towards reisomerization with half-lives ranging from 9 to 300 hours.