What is 9-bbn?

9-Borabicyclo[3.3.1]nonane, commonly known as 9-BBN, is an organoboron compound that is widely used in organic synthesis as a hydroboration reagent. Here's some information about it:

• Structure and Properties: 9-BBN is a bicyclic compound with the formula C8H15B. It exists as a white solid. It is typically handled as a solution in solvents like tetrahydrofuran (THF) or dichloromethane (DCM). The boron atom is electron-deficient and therefore electrophilic.

• Hydroboration: The primary use of 9-BBN is in hydroboration. It selectively adds across alkenes and alkynes, placing the boron atom on the less hindered carbon. This allows for subsequent reactions such as oxidation to alcohols, protonolysis to alkanes, or cross-coupling reactions.

• Stereoselectivity: 9-BBN is known for its high stereoselectivity in hydroboration reactions. The bulky bicyclic structure hinders the approach of the reagent from one side of the alkene or alkyne, leading to preferential addition from the less hindered face.

• Regioselectivity: It also exhibits high regioselectivity in hydroboration. Due to the steric bulk, boron adds preferentially to the less substituted carbon atom of the alkene or alkyne.

• Applications: 9-BBN is used in a variety of organic transformations, including:

  • Synthesis of alcohols via oxidation of the borane intermediate.
  • Synthesis of alkyl halides via halogenation of the borane intermediate.
  • Suzuki-Miyaura coupling reactions to form carbon-carbon bonds.
  • Asymmetric synthesis when used with chiral ligands or substrates.

• Advantages: Compared to other hydroboration reagents such as borane (BH3) or diborane (B2H6), 9-BBN offers improved selectivity and is often easier to handle.

• Handling and Safety: 9-BBN is air-sensitive and moisture-sensitive. It should be handled under an inert atmosphere (e.g., nitrogen or argon) using standard Schlenk techniques or in a glovebox. It is also a flammable and corrosive substance. Appropriate personal protective equipment (PPE) should be worn when handling it.