Rhodium-catalysed tetradehydro-Diels–Alder reactions of enediynes via a rhodium-stabilized cyclic allene |
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| Authors: | Srinivas Thadkapally Kaveh Farshadfar Melanie A Drew Christopher Richardson Alireza Ariafard Stephen G Pyne Christopher J T Hyland |
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| Institution: | School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong NSW 2522 Australia.; School of Physical Sciences, University of Tasmania, Hobart TAS 7018 Australia ; Department of Chemistry, Islamic Azad University, Central Tehran Branch, Poonak Tehran 1469669191 Iran |
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| Abstract: | Efficient methods for the synthesis of fused-aromatic rings is a critical endeavour in the creation of new pharmaceuticals and materials. A direct method for preparing these systems is the tetradehydro-Diels–Alder reaction, however this is limited by the need for harsh reaction conditions. A potential, but underdeveloped, route to these systems is via transition metal-catalysed cycloaromatisation of ene-diynes. Herein, tethered unconjugated enediynes have been shown to undergo a facile room-temperature RhI-catalysed intramolecular tetradehydro-Diels–Alder reaction to produce highly substituted isobenzofurans, isoindolines and an indane. Furthermore, experimental and computational studies suggest a novel mechanism involving an unprecedented and complex RhI/RhIII/RhI/RhIII redox cycle involving the formation of an unusual strained 7-membered rhodacyclic allene intermediate and a RhIII-stabilized 6-membered ring allene complex.Room temperature Rh-catalysed tetradehydro-Diels–Alder reaction via an unusual Rh-stabilised allene. |
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