- Four- and Sixfold Tandem-Domino Reactions Leading to Dimeric Tetrasubstituted Alkenes Suitable as Molecular Switches
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A highly efficient palladium-catalyzed fourfold tandem-domino reaction consisting of two carbopalladation and two C-H-activation steps was developed for the synthesis of two types of tetrasubstituted alkenes 3 and 6 with intrinsic helical chirality starting from substrates 1 and 4, respectively. A sixfold tandem-domino reaction was also developed by including a Sonogashira reaction. 20 compounds with different substitution patterns were prepared with yields of up to 97%. Structure elucidation by X-ray crystallography confirmed helical chirality of the two alkene moieties. Photophysical investigations of some of the compounds showed pronounced switching properties through light-controlled changes of their stereochemical configuration.
- Tietze, Lutz F.,Waldecker, Bernd,Ganapathy, Dhandapani,Eichhorst, Christoph,Lenzer, Thomas,Oum, Kawon,Reichmann, Sven O.,Stalke, Dietmar
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supporting information
p. 10317 - 10323
(2015/09/01)
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- An improved synthesis of dibenzofurans by a free-radical cyclization
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Reaction conditions for the formation of dibenzofurans from diazotized o-(aryloxy)anilines have been examined. Several promoters (hydroquinone, SnCl2, NaI, CuSO4, FeSO4, etc.) have been discovered; these act as electron donors and promote a free-radical mechanism. The best of these is FeSO4 which shortens the reaction time from hours to minutes and contributes to high yields (77-83%). We have been able to transform the cyclization to a reliable and convenient synthesis.
- Wassmundt,Pedemonte
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p. 4991 - 4994
(2007/10/03)
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