A Novel One-Step Synthesis of Imidazo[5,1-a]isoquinolines via a Tandem Pd-Catalyzed Alkylation−Direct Arylation Sequence

Imidazopyridine Family: Versatile and Promising Heterocyclic Skeletons for Different Applications

In recent years, there has been increasing attention focused on various products belonging to the imidazopyridine family; this class of heterocyclic compounds shows unique chemical structure, versatile optical properties, and diverse biological attributes. The broad family of imidazopyridines encompasses different heterocycles, each with its own specific properties and distinct characteristics, making all of them promising for various application fields. In general, this useful category of aromatic heterocycles holds significant promise across various research domains, spanning from material science to pharmaceuticals. The various cores belonging to the imidazopyridine family exhibit unique properties, such as serving as emitters in imaging, ligands for transition metals, showing reversible electrochemical properties, and demonstrating biological activity. Recently, numerous noteworthy advancements have emerged in different technological fields, including optoelectronic devices, sensors, energy conversion, medical applications, and shining emitters for imaging and microscopy. This review intends to provide a state-of-the-art overview of this framework from 1955 to the present day, unveiling different aspects of various applications. This extensive literature survey may guide chemists and researchers in the quest for novel imidazopyridine compounds with enhanced properties and efficiency in different uses.

Ortho/Ipso Alkylborylation of Aryl Iodides

This work describes a method for the difunctionalization of aryl iodides to generate polysubstituted arenes via Pd catalysis. The reaction hinges on the unique interplay between norbornene and the metal catalyst to impart a guided ortho C-H alkylation event followed by a programmatic ipso borylation to provide a diverse array of substituted arene products. The utility of this transformation is demonstrated through the functionalization of the boronic ester to a variety of valuable functionalities.

Palladium/Norbornene Cooperative Catalysis

Palladium/norbornene cooperative catalysis has emerged as a distinct approach to construct polyfunctionalized arenes from readily available starting materials. This Review provides a comprehensive overview of this field, including the early stoichiometric investigations, catalytic reaction developments, as well as the applications in the syntheses of bioactive compounds and polymers. The section of catalytic reactions is divided into two parts according to the reaction initiation mode: Pd(0)-initiated reactions and Pd(II)-initiated reactions.

Alkylating Reagents Employed in Catellani-Type Reactions

The Catellani reaction is a powerful strategy that allows the expeditious synthesis of highly substituted arenes, which are not easily accessible through traditional transition-metal-catalyzed cross-coupling reactions. This reaction utilizes the synergistic interplay of palladium and norbornene catalysis to facilitate sequential ortho-C-H functionalization and ipso termination of aryl iodides in a single operation. Since pioneering work by the group of Catellani in 1997, and later by the group of Lautens, this chemistry has attracted considerable attention from the synthetic chemistry community. Dramatic progress has been made by a number of groups in the past two decades. In this Minireview, the alkylating reagents employed in this intriguing reaction and the corresponding applications in organic synthesis are summarized; thus complementing existing reviews to inspire future developments.

The palladium/norbornene-catalyzed ortho-silylmethylation reaction: a practical protocol for ortho-functionalized one-carbon homologation of aryl iodides

We reported the introduction of a functionalized methyl group into the ortho-position using the Catellani reaction.

Palladium/norbornene chemistry: an unexpected route to methanocarbazole derivatives via three Csp3–Csp2/Csp3–N/Csp2–N bond formations in a single synthetic sequence

A simple route to obtain fused indolinesviaa palladium-catalyzed norbornene-mediated Heck reaction/C–H activation/double amination cascade is described.

Palladium-catalyzed ring opening of norbornene: efficient synthesis of methylenecyclopentane derivatives

The first palladium-catalyzed ring opening of norbornene to prepare methylenecyclopentane derivatives has been established.