Organoboron

Organoboron compounds are chemical species that contain carbon–boron bonds. They encompass a broad range of structures, from simple alkyl or aryl boranes to boronic acids, boronate esters, and related boron-containing reagents. The boron center is typically trivalent and sp2-hybridized, bearing an empty p orbital that confers Lewis acidity and polarizes the C–B bond. This combination makes many organoboron reagents stable enough to handle under modest conditions while remaining reactive in key transformations.

Common classes include boranes (R2BH and RBH2) as well as boronic acids RB(OH)2 and boronate esters such as RB(OR')2 or BPin derivatives, where BPin denotes the pinacolato boronate. Organoborane reagents also include vinyl and aryl boranes and alkyl boranes. The wide structural variety allows selective transformations across a broad range of substrates.

Two of the most important applications are hydroboration and cross-coupling. Hydroboration of alkenes or alkynes with borane reagents followed by oxidation gives alcohols (anti-Markovnikov hydration) or other functional groups. In cross-coupling, Suzuki–Miyaura reactions use boronic acids, esters, or boronates with palladium catalysts to form C–C bonds with aryl or vinyl partners; this is a cornerstone of modern organic synthesis. Other reactions include Chan–Lam coupling and various borylation strategies, often employing reagents such as bis(pinacolato)diboron (B2Pin2).

Synthesis and availability: organoboron compounds are prepared by hydroboration of alkenes or alkynes, by oxidation or transesterification of boranes and boronates, or by metal-catalyzed C–H borylation. They serve as versatile building blocks for pharmaceuticals, agrochemicals, and materials. Safety and handling depend on the specific compound; some borane reagents are air- or moisture-sensitive and can be pyrophoric, while many boronic esters are stable under standard laboratory conditions.