The exponential increase in the number of catalytic transformations that involve a metal-promoted activation of hitherto considered inert C−H bonds is promoting a fundamental change in the field of synthetic chemistry. Although most reactions involving C−H activations consist of simple functionalizations or additions, recent years have witnessed an upsurge in related transformations that can be formally considered as cycloaddition processes. These transformations are particularly appealing from a synthetic perspective because they allow the conversion of readily available substrates into highly valuable cyclic products in a rapid and sustainable manner. In many cases, these annulations involve the formation of metallacyclic intermediates that resemble those proposed for standard metal-catalyzed cycloadditions of unsaturated precursors.

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Metal-Catalyzed Annulations through Activation and Cleavage of C-H Bonds.

Synthetic approaches, functionalization and therapeutic potential of quinazoline and quinazolinone skeletons: The advances continue

Triazine-based covalent organic polymers (COPs) constructed from triazine or nitrile containing precursors via covalent bonding are becoming an important sub-class of porous organic framework materials for a range of applications. In particular, these materials have been proposed as a new catalyst or support material for a variety of liquid phase organic transformation reactions owing to their tunable porous structures with high surface area, high nitrogen contents, high stability in both organic and aqueous media, and relatively easy synthesis. This review article summarizes the current research activities devoted to the synthesis and characterization of new triazine-based COP materials, and their applications for heterogeneous catalysis aiming at fine chemicals synthesis are presented with critical comments.

Triazine-based covalent organic polymers: design, synthesis and applications in heterogeneous catalysis

Dimethyl sulfoxide (DMSO) is one of the most commonly applied organic solvents in chemical transformations and is utilized widely in industrial processes as well. During the past decades, numerous procedures using DMSO as a reaction reagent have been developed and published. In this review, the main developments on the employment of DMSO as sources of Me, SMe, SO2Me, as an oxidant etc. have been summarized and discussed.

The Applications of Dimethyl Sulfoxide as Reagent in Organic Synthesis

Quinazolinones, an important class of fused heterocyclic alkaloids has attracted high attention in organic and medicinal chemistry due to their significant and wide range of biological activities. There are approximately 150 naturally occurring quinazolinone alkaloids known till 2005. Several new quinazolinone alkaloids (∼55) have been isolated in the last decade. Natural quinazolinones with exotic structural features and remarkable biological activities have incited a lot of activities in the synthetic community towards the development of new synthetic strategies and approaches for the total synthesis of quinazolinone alkaloids. This review is focused on these advances in the chemistry of quinazolinone alkaloids in the last decade. This article covers the newly isolated quinazolinone natural products with their biological activities and the recently reported total syntheses of quinazolinone alkaloids from 2006 to 2015.

Recent developments in the chemistry of quinazolinone alkaloids

The 4(3H)-quinazolinone is a frequently encountered heterocycle with broad applications including antimalarial, antitumor, anticonvulsant, fungicidal, antimicrobial, and anti-inflammatory. The current review article will briefly outline the new routes and strategies for the synthesis of valuable 4(3H)-quinazolinones.

Recent advances in 4(3H)-quinazolinone syntheses

A new approach for the facile synthesis of fused quinazolinone scaffolds through a palladium-catalyzed carbonylative coupling followed by an intramolecular nucleophilic aromatic substitution is described. The base serves as the key modulator: Whereas DBU gives rise to the linear isomers, Et3N promotes the preferential formation of angular products. Interestingly, a light-induced 4+4 reaction of the product was also observed.

Base-Controlled Selectivity in the Synthesis of Linear and Angular Fused Quinazolinones by a Palladium-Catalyzed Carbonylation/Nucleophilic Aromatic Substitution Sequence†

A novel palladium-catalyzed CO-gas- and autoclave-free protocol for the synthesis of 11H-pyrido[2,1-b]quinazolin-11-ones has been developed. Quinazolinones, which are omnipresent motif in many pharmaceuticals and agrochemicals, were prepared in good yields by C-H bond activation and annulation using DMF as the CO surrogate. A (13) CO-labelled DMF control experiment demonstrated that CO gas was released from the carbonyl of DMF with acid as the promotor. The kinetic isotope effect (KIE) value indicated that the C-H activation step may not be involved in the rate-determining step. This methodology is operationally simple and showed a broad substrate scope with good to excellent yields.

Palladium-Catalyzed Carbonylative Cyclization of Arenes by C-H Bond Activation with DMF as the Carbonyl Source.

We describe here a novel procedure for the synthesis of highly substituted 2-quinolinones. By this newly developed approach, 2-quinolinone derivatives were prepared in moderate to good yields by carbonylative cyclization of N-aryl-pyridine-2-amines and internal alkynes by CH activation. Remarkably, [Mo(CO)6 ] was applied as a solid CO source and the reaction proceeded in an atom economic manner.

Palladium‐Catalyzed Carbonylative [3+2+1] Annulation of N‐Aryl‐Pyridine‐2‐Amines with Internal Alkynes by C ? H Activation: Facile Synthesis of 2‐Quinolinones

Jianbin Chen

Papers

Recent advances in 4(3H)-quinazolinone syntheses

Base-Controlled Selectivity in the Synthesis of Linear and Angular Fused Quinazolinones by a Palladium-Catalyzed Carbonylation/Nucleophilic Aromatic Substitution Sequence†

Palladium-Catalyzed Carbonylative Cyclization of Arenes by C-H Bond Activation with DMF as the Carbonyl Source.

Palladium‐Catalyzed Carbonylative [3+2+1] Annulation of N‐Aryl‐Pyridine‐2‐Amines with Internal Alkynes by C ? H Activation: Facile Synthesis of 2‐Quinolinones

Pd/C-catalyzed carbonylative C–H activation with DMF as the CO source