Hydroboration-Oxidation is a two-step chemical reaction used to convert alkenes into alcohols. In the first step, hydroboration, a borane compound adds across the double bond of the alkene, resulting in an organoborane intermediate. This process occurs in a syn addition manner, meaning both hydrogen and boron add to the same side of the double bond. In the second step, oxidation occurs when the organoborane is treated with hydrogen peroxide and a base, typically sodium hydroxide. This transforms the boron atom into a hydroxyl group, yielding an alcohol. The overall reaction is useful for producing alcohols with anti-Markovnikov selectivity.