Original: His main interests in organometallic chemistry and synthetic chemistry are catalysts, notably Grubbs' catalyst for olefin metathesis and ring-opening metathesis polymerization with cyclic olefins such as norbornene.
Simplified: His main interest is for organometallic chemistry and organic chemistry. These interests are for catalysts, such as Grubbs' catalyst for olefin metathesis and ring-opening metathesis polymerization and norbornene.