Synthesis of Tetrahydropyran/ tetrahydrofuran derivatives

In this book a metal-free protocol for the synthesis of 2 3 6-trisubstituted tetrahydropyrans using molecular iodine under mild conditions; Prins/Ene cyclisation and Prins/Ene bicyclization process for the stereoselective synthesis of a novel series of spiropyrolidine derivatives; a novel bicyclization strategy for the synthesis of indeno [21-c]pyran and cyclopenta[c]pyran scaffolds from aldehydes and exo-olefinic diols and a novel one-pot strategy has been developed for the synthesis of 3''44''5-tetrahydro-2H2''H-spiro[furan-31''-naphthalen]-2''-one scaffolds through a pinacol 12-shift terminated Prins cyclization explained very efficiently. In contrast with the rapidly growing interest in such reactions little effort has been focused on construction of O-containing heterocyclic scaffolds.These processes would be extremely useful for obtaining O- Heterocycles which comprises around 60% of all drug substances. Though few reports are there still exploration in this field is highly desirable. These observations led us to choose Prins type cascade cyclizations as a key topic for our research.