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Exploration of 9-Bromo[7]helicene Reactivity
Žádný, Jaroslav ; Jakubec, Martin ; Velíšek, Petr ; Sýkora, Jan ; Storch, Jan
Our new microwave assisted photodehydrocyclisation and completely reviewed synthetic approach for a multi-gram scale production of 9-bromo-[7]helicene led us to explore the reactivity of this compound mainly in Pd-catalysed reactions and to the further functionalization of this molecule. Next to other transformations, palladium catalysed carbon – heteroatom coupling reactions provide a large portfolio of racemic helicenes bearing different functional groups in good to excellent yields. Many of the reactions are performed in the microwave initiator saving reaction time to a minimum comparing with conventional and known synthetic methods. Such prepared compounds can undergo further synthetic reactions or can be used on a field of molecular electronics, surface chemistry or in other applications. The separation of racemic mixtures is under running in our lab. Optically pure compounds of such a type can open new possibilities in their use.
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Design and Synthesis of Helicene like Molecules
Bernard, Martin ; Sýkora, Jan ; Storch, Jan
Azahelicenes are unique inherently chiral three-dimensional aromatic compounds with high potential in homogenous assymetric catalysis. Their synthesis has many drawbacks and cannot be done in multigram scale so far. Recently, we have developed a route to new type of helicene-like molecules II. Multigram-scale synthesis of model compound where two benzene rings in [6]helicene skeleton are replaced by cyclopentadiene rings was accomplished in three steps. Such molecules have helical structure similar to helicenes, however, lower racemization barrier. Appropriately modified aza-analogues could be suitable catalysts for asymmetric reactions. Therefore, our synthetic approach leading to these compounds will be discussed.
Plný tet: 20120415230504 -  PDF
Plný text: content.csg - PDF
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