Final answer:
Anti-Markovnikov addition of water to an alkene results in the hydroxyl group attaching to the less substituted carbon, often using hydroboration-oxidation with borane and hydrogen peroxide as a typical mechanism.
Step-by-step explanation:
The stereochemistry involving the anti-Markovnikov addition of water to an alkene is characterized by the addition of the hydroxyl group (OH-) to the less substituted carbon, resulting in the formation of an alcohol. In contrast to Markovnikov's rule, which states that the hydrogen from the adding water molecule (H-OH) will attach to the carbon with the most hydrogen atoms already present, anti-Markovnikov hydration often involves a hydroboration-oxidation sequence or other radical mechanisms, leading to the installment of the hydroxyl group at the less substituted carbon.
One common way to achieve this is through the use of a catalyst like borane (BH3), followed by oxidation with hydrogen peroxide (H2O2). When borane is added to an alkene, it forms a four-membered transition state, adding boron to the more substituted carbon atom and hydrogen to the less substituted carbon atom, all while maintaining a syn addition. After oxidation, the boron atom is then replaced by a hydroxyl group, leading to the alcohol product with anti-Markovnikov stereochemistry.