Aryne Radical Chemistry
Final Report Abstract
The application of arynes as radical acceptors has been achieved within the frame of this project. The stable radical TEMPO (2,2,6,6-tetramethyl piperidine 1-oxyl) was found to add to various ortho-substituted benzynes generating the corresponding aryl radicals, which engage in 5-exo or 6-endo cyclizations. The cyclized radicals are eventually trapped by TEMPO. The introduced method provides ready access to various dihydrobenzofurans, oxindoles and sultones via a conceptually novel approach. It was also found that the far more challenging intermolecular transformation can be realized using an excess of the alkene acceptor. The reaction uses an in situ generated aryne, TEMPO and an alkene and the process can be considered as an oxyalkylation of an aryne with an additional oxidation step. Moreover, radical addition of TEMPO radicals to arynes with subsequent hydrogen atom transfer of the thus formed aryl radical and subsequent TEMPO trapping of the translocated C-radical could also be achieved. Finally, a novel radical annulation strategy involving arynes as acceptors for the preparation of interesting pi-systems was developed.
Publications
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Arynes as Radical Acceptors: TEMPO‐Mediated Cascades Comprising Addition, Cyclization, and Trapping. Angewandte Chemie International Edition, 60(2), 711-715.
Scherübl, Maximilian; Daniliuc, Constantin G. & Studer, Armido
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Intermolecular radical oxyalkylation of arynes with alkenes and TEMPO. Chemical Science, 15(34), 13712-13716.
Bhattacharya, Debkanta; Scherübl, Maximilian; Daniliuc, Constantin G. & Studer, Armido
