boroncatalyzed

Boroncatalyzed refers to chemical processes in which boron-containing species serve as catalysts to accelerate reactions. In boron catalysis, boron acts primarily as a Lewis acid, coordinating to substrates such as carbonyls, imines, or alkenes to increase their electrophilicity or to stabilize key intermediates. Boron catalysts can be simple boron reagents such as boranes and boron trihalides, boronic acids and boronate esters, or more complex organoboron frameworks including chiral boron compounds. A prominent family is frustrated Lewis pairs (FLPs), in which a boron Lewis acid and a bulky Lewis base operate cooperatively to activate substrates without forming a stable adduct.

Mechanistically, boron catalysts often work by binding to a heteroatom or π-system, promoting bond activation, rearrangement, or hydride/boryl transfer cycles, and then regenerating the active boron species to continue turnover. Catalysis may be purely Lewis acid–base, or may involve cooperative interactions with other catalysts or co-catalysts.

Applications of boron catalysis span organic synthesis and materials chemistry. It is used to promote a variety of transformations, including the activation of carbonyl compounds, activation and functionalization of small molecules, and the initiation or mediation of polymerization processes, frequently under metal-free or mild conditions. The field encompasses both achiral and enantioselective transformations, with chiral organoboron catalysts enabling asymmetric variants.

Advantages of boron catalysts include metal-free operation, tunable Lewis acidity through different boron substituents, and compatibility with a broad range of functional groups. Limitations include sensitivity to moisture and air for many boron reagents, variable turnover numbers, and the need for careful catalyst design to balance reactivity and stability.

See also: boron chemistry, Lewis acid catalysis, frustrated Lewis pair.