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Piers' Borane-Induced Tetramerization of Arylacetylenes
Max Hasenbeck1, Tizian Müller1, Arthur Averdunk1
1Institut für Organische Chemie, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 17, 35392, Gießen, Germany.
Abstract:
We herein report that the reaction of Piers' borane, i. e. HB(C6 F5 )2 , with an excess of arylacetylenes at room temperature leads to tetramerization of the acetylene and the diastereoselective formation of boryl-substituted tetra-aryl-tetrahydropentalenes. The reaction mechanism was investigated by isotope labeling experiments and DFT computations. These investigations indicate that a series of 1,2-carboboration reactions form an octatetraene that undergoes an electrocyclization. Two skeletal rearrangements then presumably lead to the formation of the tetrahydropentalene core. Overall, this intricate and unprecedented transformation comprises five carbon-carbon bond formations in a single reaction.
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