title: Palladium-Catalyzed Intramolecular Fujiwara-Hydroarylation: Synthesis of Benzo[a]phenazines Derivatives.
abstract: An atom-economical Pd-catalyzed approach for the synthesis of benzophenazine derivatives using substituted 2-aryl-3-(aryl/alkylethynyl) quinoxaline in the presence of trifluoroacetic acid at 65 °C has been described. The chemistry involves in situ generation of cationic Pd(II) species, which functionalized the aromatic C-H bonds via electrophilic metalation followed by concomitant intramolecular trans-insertion of C-C triple bond to aryl-Pd complex. The results were supported by various control experiments including with electron-deficient arenes and deuterium labeling studies. The deuterium labeling studies supports electrophilic palladation of aromatic C-H over activation of C-C triple bond of alkyne. The structure of synthesized compounds was further confirmed by X-ray crystallography studies. This catalytic protocol has been efficiently applied for novel synthesis of highly functionalized benzo fused phenazines.
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Sonu
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Saunthwal
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Mujahid
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Trapti
authors.initials: T
authors.lastname: Aggarwal
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Akhilesh K
authors.initials: AK
authors.lastname: Verma