Dihydroxylation reactions involve the stereospecific addition of two hydroxyl groups across a carbon–carbon double bond, producing vicinal diols. Understanding the stereochemical outcomes—such as the formation of (d,l)-butane-2,3-diol from trans-but-2-ene and meso-butane-2,3-diol from cis-but-2-ene—requires analyzing the syn addition mechanism and selecting appropriate reagents like osmium tetroxide (OsO₄) or potassium permanganate (KMnO₄).

Practice problems focus on identifying reagents that achieve these conversions and interpreting stereochemical results. Key skills include:

Applying concepts of syn versus anti addition
Predicting stereoisomeric products based on alkene geometry
Distinguishing between enantiomeric and meso diols

Syn Vicinal Dihydroxylation: Videos & Practice Problems