The book "Synthesis of Tetrahydropyran/tetrahydrofuran derivatives" offers a comprehensive investigation of innovative synthesis methods for O-containing heterocyclic compounds. It describes a metal-free approach for the synthesis of 2, 3, 6-trisubstituted tetrahydropyrans under mild conditions, using molecular iodine. Additionally, various cyclization processes, such as the Prins/Ene cyclization, are presented, leading to the stereoselective synthesis of novel spiropyrrolidine derivatives. The authors also introduce a novel bicyclization strategy for the synthesis of Indeno[2,1-c]pyran and Cyclopenta[c]pyran frameworks from aldehydes and exo-olefinic diols. Another highlight is the development of an efficient one-pot strategy for synthesizing 3',4,4',5-Tetrahydro-2H,2'H-spiro[furan-3,1'-naphthalen]-2'-one frameworks. These methods are particularly relevant, as O-containing heterocycles account for about 60% of all pharmaceuticals, making research in this area of great importance.