De Novo Protocol for the Construction of Benzo[a]fluorenes via Nitrile/Alkene Activation
Babasaheb Sopan Gore1, Chun-Hsien Chiang1, Chein Chung Lee1
1Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, No. 100, Shiquan First Road, Sanmin District, Kaohsiung City 807, Taiwan.
Abstract:
Unprecedented chemo- and regioselective synthesis of benzo[a]fluorenes and naphthamide-substituted benzo[a]fluorenes were constructed from the reaction of (E)-2-aroyl-3-(2-(arylalkynes/alkenes)aryl)acrylonitrile scaffolds under metal-free conditions via the activation of nitriles and alkenes, respectively. A tentative reaction mechanism was proposed for this homofunctionalization of nitriles. Control experiments showed that the reaction proceeds via selective nitrile or alkene protonation, depending upon the substrates. Additionally, we demonstrated an alternative expeditious route for the synthesis of disubstituted benzo[a]fluorenes in the presence of TfOH alone.
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