Michael McBride continues Yale's Freshman Organic Chemistry II (CHEM 125B) with a lecture on how metal catalysts control alkene reactions. He opens with dihydroxylation of alkenes by permanganate and osmium tetroxide, then turns to catalytic hydrogenation, explaining how metal orbitals allow simultaneous oxidative addition and reductive elimination of hydrogen across a double bond. McBride challenges the textbook claim that hydrogenation is always syn, showing primary literature evidence for anti addition when allylic rearrangement occurs on the catalyst surface. The lecture moves on to olefin metathesis and metal-catalyzed polymerization, with attention to how catalyst design governs polymer tacticity, contrasting this control with the less selective outcomes of free-radical and acid-catalyzed polymerization. He closes with electrophilic oligomerization and the natural coagulation of latex into rubber. Chapter markers divide the fifty-one-minute talk into six sections tracking each mechanism in sequence.