BH3THF

BH3·THF, commonly written as BH3·THF, is the borane-tetrahydrofuran complex. It is a stabilized source of borane used in organic synthesis. In this adduct, tetrahydrofuran coordinates to boron, moderating the reactivity of borane and enabling storage and handling as a solution in THF. The complex is typically prepared commercially as a solution in dry THF or formed in situ by dissolving borane in dry THF under inert atmosphere.

Reactivity and applications: BH3·THF serves as a versatile boron reagent. In hydroboration, it adds across alkenes and alkynes to form organoboranes that, upon oxidation with hydrogen peroxide and sodium hydroxide, yield anti-Markovnikov alcohols. The boron centers can be further transformed to various organoboron compounds used in cross-coupling reactions such as Suzuki–Miyaura couplings. BH3·THF also reduces carboxylic acids to primary alcohols under appropriate conditions, with other carbonyl groups typically reduced more slowly.

Handling and safety: BH3·THF is moisture- and air-sensitive and is typically handled under inert gas. Contact with water liberates hydrogen gas and boric acid derivatives; it can be a fire and irritant hazard. Store at low temperature in a dry, inert environment and use with appropriate personal protective equipment and ventilation.

See also: borane reagents such as borane-dimethyl sulfide (BMS) and other borane-thf complexes.