This book opens with a discussion on the syntheses of acyclic polyketides by using epoxide opening reactions. The stereoselective epoxidations of allylic alcohols, including catalytic asymmetric epoxidation reactions and stereospecific reactions due to substrate-control, are described shortly. Afterwards, different epoxide opening reactions and applications in natural product synthesis are reviewed. The authors highlight the recent advances in catalytic one-pot synthesis of epoxides. The versatility of organometallic catalysts in epoxidation of alkenes are considered an important point of research in the context of these transformations. Later, occurrence of carotenoid 5,6-epoxides, their chemical synthesis, the separation of stereoisomers, some transformations of 5,6-epoxy-carotenoids, and their biological processes are described. Following this, the methodologies for the deoxygenation of epoxides using oxo-molybdenum and oxo-rhenium complexes as efficient catalysts are described, allowing a large community of readers, in particularly the community that works in catalysis, organic and organometallic chemistry, ready access to the novel methodologies developed.