Gif Chemistry for Oxidation of Activated Methylenes to Ketones.

2023

J. Am. Chem. Soc.

Porphyrin contains four inwardly oriented nitrogen atoms. It is arguably the most ubiquitous multifunctional naturally occurring macrocycle that has inspired the design of novel nitrogencontaining heterocycles for decades. While cyclic tetramers of pyrrole, indole, and pyridine have been exploited as macrocycles in this category, quinoline has been largely neglected as a synthon. Herein, we report the synthesis of TEtraQuinoline (TEQ) as a 'missing link' in this N4 macrocycle family. In TEQs, four quinoline units are concatenated to produce an S 4 -symmetric architecture. TEQs are characterized by a highly rigid saddle shape, wherein the lone-pair orbitals of the four nitrogen atoms are not aligned in a planar fashion. Nevertheless, TEQs can coordinate a series of transition-metal cations (Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , and Pd 2+ ). TEQs are inherently fluorescence-silent but become strongly emissive upon protonation or complexation of Zn(II) cations (ϕ = 0.71). TEQ/Fe(II) complexes can catalyze dehydrogenation and oxygenation reactions with catalyst loadings as low as 0.1 mol %.

Section: Results and Discussionmentioning

confidence: 98%

TEtraQuinolines: A Missing Link in the Family of Porphyrinoid Macrocycles

2023

J. Am. Chem. Soc.

“…An electron-rich substrate bearing a methoxy group at the 6-position was amenable to oxidation to give 13f even at -25 °C. This new class of tetradentate ligand/Fe(II) catalysts also engaged indoline 14 and dihydroanthracene 15 in dehydrogenation and dioxygenation reactions to give indole 18 and anthraquinone 20, respectively [53][54][55] .…”

Section: Metal Complexes Of Tetraquinolines (Teqs)mentioning

confidence: 98%

TEtraQuinolines (TEQs): A missing link in the family of porphyrinoid macrocycles

2022

Preprint

Porphyrin contains four inwardly oriented nitrogen atoms. It is arguably the most ubiquitous multifunctional naturally occurring macrocycle that has inspired the design of novel nitrogen-containing heterocycles for decades. While cyclic tetramers of pyrrole, indole, and pyridine have been exploited as macrocycles in this category, quinoline has been largely neglected as a synthon. Herein, we report the synthesis of TEtraQuinoline (TEQ) as a ‘missing link’ in this N4 macrocycle family. In TEQs, four quinoline units are concatenated to produce an S4-symmetric architecture. TEQs are characterized by a highly rigid saddle shape, wherein the lone-pair orbitals of the four nitrogen atoms are not aligned in a planar fashion. Nevertheless, TEQs can coordinate a series of transition-metal cations. TEQs are inherently fluorescence-silent, but become strongly emissive upon protonation or complexation of Zn(II) cations ( = 0.71). TEQ/Fe(II) complexes can catalyse dehydrogenation and oxygenation reactions with catalyst loadings as low as 0.1 mol%.

TEtraQuinolines (TEQs): A missing link in the family of porphyrinoid macrocycles

2022

Preprint

Porphyrin contains four inwardly oriented nitrogen atoms. It is arguably the most ubiquitous multifunctional naturally occurring macrocycle that has inspired the design of novel nitrogen-containing heterocycles for decades. While cyclic tetramers of pyrrole, indole, and pyridine have been exploited as macrocycles in this category, quinoline has been largely neglected as a synthon. Herein, we report the synthesis of TEtraQuinoline (TEQ) as a ‘missing link’ in this N4 macrocycle family. In TEQs, four quinoline units are concatenated to produce an S4-symmetric architecture. TEQs are characterized by a highly rigid saddle shape, wherein the lone-pair orbitals of the four nitrogen atoms are not aligned in a planar fashion. Nevertheless, TEQs can coordinate a series of transition-metal cations. TEQs are inherently fluorescence-silent, but become strongly emissive upon protonation or complexation of Zn(II) cations ( = 0.71). TEQ/Fe(II) complexes can catalyse dehydrogenation and oxygenation reactions with catalyst loadings as low as 0.1 mol%.