Heterobiaryls

Heterobiaryls are organic compounds containing two aromatic rings linked by a single bond, where at least one of the rings is a heterocycle. A heterocycle is a cyclic compound that contains atoms of at least two different elements in its ring, most commonly carbon and at least one other element such as nitrogen, oxygen, or sulfur. The aromatic rings in heterobiaryls can be either homocyclic (composed solely of carbon atoms, like benzene) or heterocyclic themselves. The linkage between the two rings is typically a carbon-carbon single bond.

The synthesis of heterobiaryls is a significant area of research in organic chemistry due to their widespread presence in pharmaceuticals, agrochemicals, and advanced materials. They often exhibit unique electronic and physical properties that differ from their all-carbon counterparts. These properties arise from the interplay of the electronic systems of the two connected aromatic rings, influenced by the presence of heteroatoms. Common synthetic strategies include transition-metal-catalyzed cross-coupling reactions, such as Suzuki, Stille, and Negishi couplings, which are highly effective for forming the carbon-carbon bond between the aryl or heteroaryl fragments.

The structural diversity of heterobiaryls is vast, depending on the nature of the aromatic rings, the position of the heteroatoms within those rings, and the point of connection between the rings. This structural variability allows for fine-tuning of their properties for specific applications. For example, incorporating nitrogen atoms can lead to compounds with Lewis basicity, while oxygen atoms can introduce polarity. These molecules serve as important scaffolds for drug discovery, acting as key structural motifs in many biologically active compounds.