Synthesis of Conjugated Polycyclic Quinoliniums by Rhodium(III)-Catalyzed Multiple C–H Activation and Annulation of Arylpyridiniums with Alkynes

Abstract

A simple method for the efficient synthesis of highly substituted pyrido[1,2-a]quinolinium- and quinolizino[3,4,5,6-ija]quinolinium-based polyheteroaromatic compounds via rhodium(III)-catalyzed multiple C-H activation annulation reactions has been developed. Moreover, some of the quinolizino[3,4,5,6-ija]quinolinium salts exhibit intense fluorescence and have potential application in optoelectronic materials.

A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones

“…In recent years, cyclopentadienyl rhodium complexes have been extensively used for the C−H activation of aromatic compounds with various directing groups . They have opened new ways to synthesize and explore a number of valuable molecules, such as drugs and fluorophores . While most of the research has been done with the commercially available catalyst [(C 5 Me 5 )RhCl 2 ] 2 , considerable attention has also been paid to complexes with other cyclopentadienyl ligands to control the selectivity of various transformations .…”

A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones

“…[1][2][3] They have opened new ways to synthesize and explore an umber of valuable molecules,s uch as drugs [4] and fluorophores. [5,6] While most of the research has been done with the commercially available catalyst [(C 5 Me 5 )RhCl 2 ] 2 ,c onsiderable attention has also been paid to complexes with other cyclopentadienyl ligands to control the selectivity of various transformations. [7][8][9][10][11] In this field, the development of chiral catalysts is the most challenging.…”

Modern Synthetic Avenues for the Preparation of Functional Fluorophores

“…For instance, Cheng and co‐workers described rhodium‐catalyzed annulations of 2‐aryl pyridines and alkynes under O 2 atmosphere to prepare fluorescent pyridinium salts with potential applications in organic electronic devices 34. Similarly, Wang and co‐workers prepared polycyclic quinolinium cations in double C−H activation/annulation processes (Figure 5 I) 35. Hua and Zheng reported oxidative coupling reactions with [(RhCl 2 Cp*) 2 ] (Cp*=pentamethylcyclopentadienyl) as the catalyst to obtain complex heterofused phenanthroimidazoles in very good yields (Figure 5 J) 36.…”