Rh^III‐Catalyzed Direct C8‐Arylation of Quinoline N‐Oxides using Diazonaphthalen‐2(1H)‐ones: A Practical Approach towards 8‐aza BINOL

Abstract

An efficient Rh -catalyzed redox-neutral method for the direct C8-arylation of quinoline N-oxides using diazonaphthalen-2(1H)-one as coupling partner has been demonstrated. The developed method is simple, scalable and straightforward with a wide range of substrate scope. The applicative potential was extended with a late-stage functionalization and straightforward synthesis of 8-azaBINOL derivative. A plausible reaction pathway was proposed after carrying out preliminary control studies.

Rhodium‐Catalyzed Selective C−H Bond Functionalization of Quinolines

“…The application of the reaction done with the late-stage functionalization of cinchonidine derivative and scale up the reaction up to gram level (Scheme 17). [41] In 2018, Cui and coworkers developed a methodology for the C(8)À H amination by using commercially available unactivated trifluoroacetamide. The reaction was performed under air and require only 1 hour for the completion.…”

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

“…Direct site‐selective C−H bond functionalizations of quinoline are a recent subject of interest . In particular, significant progress has been made on direct introduction of various functional groups at its C8 position by others and us . In pioneering work, Chang's group elegantly established C8‐amidation of quinoline N ‐oxides under Ir III[10] and Rh III[11] catalysis using various amidating sources.…”

“…[7] In particular, significant progress has been made on direct introduction of various functional groups at its C8 position by others [8] and us. [9] In pioneering work, Chang's group elegantly established C8-amidation of quinoline N-oxides under Ir III[10] and Rh III [11] catalysis using variousa midating sources. Loh and co-workersa lso established an Rh III -catalyzed alternative strategy for the C8-amidation of quinoline N-oxide using amidobenziodoxolone as the coupling partner.…”

“…[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).…”

Palladium‐Catalyzed Regioselective C−H Arylation of Quinoline‐N‐Oxides at C‐8 Position using Diaryliodonium Salts

“…On the other hand, Chang's strategy suffers from limited substrate scope and poor yields. Recently, Samanta's group demonstrated direct C‐8 arylation of quinoline‐ N ‐oxides using diazonaphthalen‐2(1 H )‐one as arylating agent using expensive Rh‐catalyst and Ag salt as an additive and the reaction scope has been limited to naphthalenes [Scheme (iv)]. Very recently, Chang and co‐workers again demonstrated Ru‐catalyzed deoxygenative regioselective C‐8 arylation of quinoline‐ N ‐oxides with arylboronic esters [Scheme (v)] .…”