hydroborointia

Hydroboration is a chemical reaction where a boron-hydrogen bond adds across a carbon-carbon double or triple bond. Typically, this reaction involves a borane reagent, such as BH3, which can be used directly or complexed with a Lewis base like tetrahydrofuran (THF). The addition of the boron and hydrogen atoms across the pi bond is regioselective, meaning it preferentially occurs at one carbon atom over the other. In most cases, the boron atom attaches to the less substituted carbon of the double or triple bond, and the hydrogen atom attaches to the more substituted carbon. This anti-Markovnikov addition is a key characteristic of hydroboration.

The stereochemistry of hydroboration is also notable. The addition is syn, meaning both the boron and hydrogen atoms add to the same face of the pi bond. This syn addition is often followed by subsequent reactions that proceed with retention of configuration at the carbon atoms. The most common subsequent reaction after hydroboration is oxidation, typically with hydrogen peroxide in a basic solution. This oxidation step replaces the boron atom with a hydroxyl group, resulting in the formation of an alcohol. Due to the anti-Markovnikov regioselectivity and syn stereochemistry of the initial hydroboration step, the overall hydroboration-oxidation sequence leads to the syn-addition of water across the double or triple bond in an anti-Markovnikov fashion, producing primary alcohols from terminal alkenes. Hydroboration is a versatile reaction in organic synthesis, widely used for the preparation of alcohols and other functionalized compounds.