Benzoannulation of aromatic heterocycles: advances in the 21st century

Benzoannulated aromatic heterocycles (BAHs), also known as benzoheterocycles, are key building blocks in the development of functional materials and pharmaceuticals. They are involved in a variety of biochemical processes in nature. The prevalence and widespread use of these molecules stimulates the chemical community's ongoing interest in developing methods to construct carbazole, indole, quinoline, isoquinoline and benzo[b]thiophene motifs. The most common strategy for preparing them is the heteroannulation of functionalized benzene derivatives. Over the last two decades, an alternative approach based on the annulation of heterocyclic derivatives has been developed: benzoannulation, also known as benzannulation. Compared to classical heteroannulation, this approach has several advantages and has led to significant progress in the availability of a variety of benzoheterocycles in recent years. This review is the first to analyze the development of benzoannulation methods for aromatic heterocycles in the 21st century. We highlight the advantages of the benzoannulation strategy, including the versatility of the methods, the availability of starting compounds and the ability to obtain products with specified substituents in the benzene ring. This review aims to help chemists with the synthesis of benzoheterocycles of a specific structure for various applications, ranging from the design of biologically active compounds and the synthesis of natural products to materials chemistry.
The bibliography includes 298 references.