- Apparent alkyl transfer and phenazine formation via an aryne intermediate
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Treatment of chlorotriaryl derivatives 3a and 3d or fluorotriaryl derivatives 3b and 3e with potassium diisopropylamide afforded alkyl-shifted phenazine derivatives 5a/5b, rather than the expected 9-membered triazaorthocyclophane 2a. The phenazine derivatives were isolated in 78-98% yield depending on the halogen and alkyl group present. In the absence of the halogen (chloro or fluoro), the apparent alkyl shift proceeds more slowly and cannot proceed via the intermediacy of the aryne intermediate. Mechanistic possibilities include intramolecular nucleophilic attack on an aryne intermediate leading to a zwitterionic intermediate and alkyl transfer via a 5-endo-tet process, or via a Smiles rearrangement.
- Panagopoulos, Andria M.,Steinman, Doug,Goncharenko, Alexandra,Geary, Kyle,Schleisman, Carlene,Spaargaren, Elizabeth,Zeller, Matthias,Becker, Daniel P.
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- A route to regioselectively functionalized carbazoles, dibenzofurans, and dibenzothiophenes through anionic cyclization of benzyne-tethered aryllithiums
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The treatment of 2-fluorophenyl 2-iodophenylamines, ether, and thioether, easily prepared from commercially available products, with 3.3 equiv of t-BuLi and further reaction with selected electrophiles gives rise to functionalized carbazole, dibenzofuran, and dibenzothiophene derivatives in a direct and regioselective manner. The process involves an anionic cyclization on a benzyne-tethered aryllithium intermediate.
- Sanz, Roberto,Fernandez, Yolanda,Castroviejo, Ma. Pilar,Perez, Antonio,Fananas, Francisco J.
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p. 6291 - 6294
(2007/10/03)
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