Straightforward Access to Isoindoles and 1,2-Dihydrophthalazines Enabled by a Gold-Catalyzed Three-Component Reaction

We describe herein a gold-catalyzed three-component reaction of o-alkynylbenzaldehydes, aryldiazonium salts, and trimethoxybenzene. This process enables the one-pot formation of valuable isoindoles and 1,2-dihydrophathalazines. The regioselectivity of the reaction is dictated by the nature of the aryldiazonium salt. Noticeably, the reaction is performed at room temperature under mild conditions and tolerates a variety of functional groups on both the o-alkynylbenzaldehyde and the aryldiazonium salt. Experimental mechanistic studies suggest that it is catalyzed by arylAu(III) species.

Palladium-Catalyzed Synthesis of Fused Carbo- and Heterocycles: Recent Advances

The use of palladium catalysts in fused ring synthesis has been increasingly noteworthy in recent years in organic synthesis. It has a lot of potential compared to other transition metal catalysts, because of its one-of-a-kind feature that makes them more widely applicable in a variety of disciplines application. Palladium is important in a variety of Heck processes, including intramolecular, intermolecular, and reductive Heck reactions, which produce diverse carbocycles and heterocycles of biological importance. Under optimal reaction conditions, carbocyclization or heterocyclization occurs, resulting in the production of numerous structural building blocks of naturally occurring compounds. Beside intramolecular Heck-type reactions, cycloaddition, cycloalkylation, oxidative coupling, C-H functionalization, cross-coupling reactions, and carboamidation reactions have also been employed extensively to access fused carbo- and heterocycles of immense biological importance. This review article provides a well-summarized discussion (since 2001) on fused carbo- and heterocycle ring synthesis using palladium catalysts, overviewing their applications, and mechanistic insights.

Visible-light induced isoindoles formation to trigger intermolecular Diels-Alder reactions in the presence of air

Visible-light induced isoindole formation triggered an intermolecular Diels-Alder reaction with dienophiles such as acetylenedicarboxylate and maleimides in the presence of air. The reaction resulted in excellent diastereoselctivity and high yields under mild reaction conditions. This protocol provides an atom-economical, transition-metal-free (TM-free) and straightforward approach to structurally diverse bridged-ring heterocycles from easily accessible molecules.

Palladium-catalyzed α-arylation of carbonyls in the de novo synthesis of aromatic heterocycles

Aromatic heterocycles are a very well represented motif in natural products and have found various applications in chemistry and material science, as well as being commonly found in pharmaceutical agents. Thus, new and efficient routes towards this class of compound are always desirable, particularly if they expand the scope of chemical methodology or facilitate more effective pathways to complex substitution patterns. This perspective covers recent developments in the de novo synthesis of aromatic heterocycles via palladium-catalysed α-arylation reactions of carbonyls, which is itself a powerful transformation that has undergone significant development in recent years.

A new route for the synthesis of highly substituted 4-aminoquinoline drug like molecules via aza hetero–Diels–Alder reaction

A new route has been developed for the synthesis of 4-aminoquinoline drug like moleculesviaaza hetero–Diels–Alder reaction starting from 2H-indazole as a diene for the first time.

Cycloaddition-based formal C-H alkynylation of isoindoles leading to the synthesis of air-stable fluorescent 1,3-dialkynylisoindoles

Reaction of N-alkylisoindoles with (bromoethynyl)triisopropylsilane afforded 1,3-bis(triisopropylsilylethynyl) isoindoles in high yields. The formal C-H alkynylation proceeds under transition-metal-free conditions through [4 + 2] cycloaddition of the pyrrole ring of isoindole with bromoalkyne followed by ring-opening of the product.

Synthesis of isoindoles and related iso-condensed heteroaromatic pyrroles

Over the past few years, isoindoles have found wide application in materials science. Isoindole containing BODIPY dyes are highly fluorescent materials and have been extensively used in various fields of science. Phthalocyanines, metal containing cyclic tetramers of isoindole, form coordination complexes with most elements of the periodic table. These complexes are intensely coloured and are used as pigments and dyes. However, isoindoles are relatively unstable 10π-heteroaromatic systems and few synthetic methods provide these compounds in good yields. This tutorial review will give an overview of the reported synthetic methods towards isoindoles and related heteroaromatic systems over a time span of approximately 10 years (2000 to current), including the applications where they have been reported. The importance of the field will be illustrated and factors influencing product stability will be discussed.