Rh(III)-Catalyzed C-H Olefination Cascades to Divergently Construct Diverse Polyheterocycles by Tuning Manipulations of Directing Groups

Transition Metal-Catalyzed Dual C-H Activation/Annulation Reactions Involving Internal Alkynes

Recently, transition metal-catalyzed ortho-C-H bond activation/annulations involving two internal alkyne molecules have been extensively used to synthesize highly substituted polycyclic aromatic scaffolds. Such reactions have emerged as a powerful atom and step-economical strategy for the assembly of multifunctional bioactive molecules. In this context, we focused on the recent achievements of dual C-H bond activation/annulations, as well as functionalization reactions involving diaryl/alkyl alkynes.

"One pot" synthesis of quinazolinone-[2,3]-fused polycyclic scaffolds in a three-step reaction sequence

Diverse quinazolinone-[2,3]-fused polycyclic skeletons occupy a prominent position in drug discovery. Even with currently available methods there still remain unmet needs for flexible access to such structures. Herein, we have explored a mild "one pot" procedure for the construction of various quinazolinone-[2,3]-fused polycycles. The procedure involves Pd-catalyzed carbonylation of N-(2-iodophenyl)acetamides, release of the masked terminal amine, and two sequential and spontaneous cyclizations. This generally applicable approach features easy assembly of precursors from readily available starting materials, mild reaction conditions, non-cumbersome operation, and polycyclic diversity.

Photogenerated chlorine radicals activate C(sp3)-H bonds of alkylbenzenes to access quinazolinones

An Fe-catalyzed visible-light induced condensation of alkylbenzenes with anthranilamides has been developed. Upon irradiation, the trivalent iron complex could generate chlorine radicals, which successfully abstracted the hydrogen of benzylic C-H bonds to form benzyl radicals. And these benzyl radicals were converted into oxygenated products under air conditions, which subsequently reacted with anthranilamides for the synthesis of quinazolinones.

Ru(II)-Catalyzed Regioselective C(5)-H Functionalization of Quinazolinone-Coumarin Conjugates: Synthesis and Photophysical Studies

The quinazolinone template offers an exciting potential for transforming molecules into useful bioactivity. Herein, we report the first regioselective C-5 alkenylation of quinazolinone-coumarin conjugates via ruthenium(II) catalyst using amide as a weak directing group. This methodology permits excellent regioselectivity, extensive substrate tolerance, and mild reaction conditions. In addition, it generates interesting fluorophores that show positive solvatochromism in the range from 404 nm (toluene) to 541 nm (methanol).

Regiodivergent C-N Coupling of Quinazolinones Controlled by the Dipole Moments of Tautomers

Herein, we report that the dipole moments of tautomers can be the controlling factor for regiodivergent synthesis of either 14H-quinazolino[3,2-f]phenanthridin-14-ones or 6H-quinazolino[1,2-f]phenanthridin-6-ones, selectively, from unmasked 2-([1,1'-biphenyl]-2-yl)quinazolin-4(3H)-one. An intramolecular C(sp²)-NH coupling reaction mediated by PhI(OCOOCF₃)₂ could lead to two different regioisomers selectively at different temperatures when the dielectric constants of solvents like hexafluoroisopropanol and trifluoroacetic acid matched with the tautomer's dipole moments.

On the application of 3d metals for C-H activation toward bioactive compounds: The key step for the synthesis of silver bullets

Several valuable biologically active molecules can be obtained through C-H activation processes. However, the use of expensive and not readily accessible catalysts complicates the process of pharmacological application of these compounds. A plausible way to overcome this issue is developing and using cheaper, more accessible, and equally effective catalysts. First-row transition (3d) metals have shown to be important catalysts in this matter. This review summarizes the use of 3d metal catalysts in C-H activation processes to obtain potentially (or proved) biologically active compounds.

Rhodium(iii)-catalyzed annulation of 3-arylquinazolinones with alkynes via double C–H activation: an efficient route for quinolino[2,1-b]quinazolinones

An effective method for the synthesis of quinolino[2,1-b]quinazolinones has been described.