1. When adding the borane (BH3/THF) through an addition reaction, the BH¬2 will attach to the least substituted carbon atom. This often known as being an anti-Markovnikov formation.
2. Because the reaction occurs all at once (concerted), the H and BH2 will be added to the same side of the molecule. This is known as syn addition.
3. In the last step of the reaction, hydrogen peroxide with a hydroxyl group is then added to replace the BH¬2¬ with OH. This substitution doesn’t change the stereochemistry, as the OH ends