Dual Role of Anthranils as Amination and Transient Directing Group Sources: Synthesis of 2-Acyl Acridines

Abstract

The transient directing group promoted C(sp)-H functionalization of benzaldehydes with anthranils by a cationic rhodium(III) catalyst is described. Notably, anthranils have been used as both transient directing groups and amination sources to afford 2-acyl acridines through direct C-H amination followed by acid-mediated cyclization. A range of substrate scopes and functional group tolerance were observed.

RhIII‐Catalyzed Straightforward Synthesis of Benzophenanthroline and Benzophenanthrolinone Derivatives using Anthranils

“…Very recently, Cui's group described another Rh III ‐catalyzed C8‐amidation of quinoline N ‐oxide using commercially available trifluoroacetamide . Recently, benzo[ c ]isoxazoles (anthranils) were highly successful as a bifunctional arylaminating agent under redox‐neutral conditions for the direct aryl amination of sp 2 and sp 3 C−H bonds and straightforward construction of N‐PAHs …”

“…Wang's group independently revealed a tandem Rh III ‐catalyzed amination/annulation strategy to synthesize indoloquinoline derivatives (Scheme c) . Kim's group also extensively studied Rh III ‐catalyzed synthesis of acridine derivatives using various coupling partners (Scheme d) . However, to the best of our knowledge, there is no report for the synthesis of benzophenanthroline and benzophenanthrolinone class of N‐doped PAHs using a pot‐ and step‐economic efficient strategy.…”

“…[13] Recently,b enzo[c]isoxazoles (anthranils) were highly successful as ab ifunctional arylaminating agent under redox-neutral conditions for the direct aryl amination of sp 2 and sp 3 CÀHb onds [14,15] and straightforward construction of N-PAHs. [16][17][18][19] In ar ecent report, Hashmi andc o-workers studied Au III -catalyzed construction of 2-amino pyrroles and quinoline-based polyazaheterocycles( Scheme 1a). [16a] Li's group described Rh IIIcatalyzed amination/annulation of arenes/heteroarenes using anthranils (Scheme1ba nd c).…”

“…[18] Kim's group also extensively studied Rh III -catalyzed synthesis of acridine derivatives using various coupling partners (Scheme 1d). [19] However,t ot he best of our knowledge,t here is no report for the synthesis of benzophenanthroline and benzophenanthrolinone class of N-doped PAHs using ap ot-and step-economic efficient strategy.I ntrigued by our latest studies on step-economic synthesis of N-containing extended p-conjugated systems, [9,20] we envisioned that as imilar idea might help us to obtain our desired N-containing extended p-conjugated systems. Herein, we report Rh III -catalyzed site-selective direct strategies for the pot-economic constructiono fb enzophenanthroline and step-economic synthesis of benzophenanthrolinone (Scheme1e).…”

Iron‐Mediated Ring‐Opening and Rearrangement Cascade Synthesis of Polysubstituted Pyrroles from 4‐Alkenylisoxazoles

“…Among them, the majority of the work has been focused on transition‐metal‐catalyzed transformations of isoxazoles to N ‐heterocycles. ‐ To date, most of these transformations are noble metal catalyzed intermolecular annulations, including the annulations between isoxazoles and alkynes catalyzed by platinum and gold catalysts, forming N ‐heterocycles such as 1,3‐oxazepines and 2,5‐dihydropyridines, 4 H ‐azepines, pyrroles, quinolines, indoles, and N ‐doped polycyclic aromatic hydrocarbons . Recently, the non‐noble metal catalyst Zn(OTf) 2 ‐mediated synthesis of polysubstituted pyrroles by an intermolecular annulation of isoxazoles with ynol ethers has also been reported…”