Diverse Synthesis of Fused Polyheterocyclic Compounds via [3 + 2] Cycloaddition of In Situ-Generated Heteroaromatic N-Ylides and Electron-Deficient Olefins.

[3 + 2] Cycloaddition reactions of heteroaromatic N-ylides with electron-deficient olefins have been developed. The heteroaromatic N-ylides, in situ generated from N-phenacylbenzothiazolium bromides, can smoothly react with maleimides under very mild conditions, affording fused polycyclic octahydropyrrolo[3,4-c]pyrroles in good-to-excellent isolated yields. This reaction concept could also be extended to 3-trifluoroethylidene oxindoles and benzylidenemalononitriles as electron-deficient olefins for accessing highly functionalized polyheterocyclic compounds. A gram-scale experiment was also carried out to verify the practicability of the methodology.

Aryl Methyl Ketones: Versatile Synthons in the Synthesis of Heterocyclic Compounds.

The synthesis of aromatic heterocycles has attracted substantial attention due to the abundance of these heterocycles in drug molecules, natural products, and other compounds of biological interest. Accordingly, there is a demand for straightforward synthetic protocols toward such compounds using readily available starting materials. In the past decade, there have been substantial developments in heterocycle synthesis, especially in metal-catalyzed and iodine-assisted approaches. This graphical review focuses on notable reactions from the past decade using aryl and heteroaryl methyl ketones as starting materials, including representative reaction mechanisms.