Kinetic and thermodynamic control in the cyclization via thiiranium ions. Stereoselective synthesis of a 2,3,5-trisubstituted tetrahydropyran ring

✍ Scribed by Michelangelo Gruttadauria; Renato Noto

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2001
• Tongue: English
• Weight: 38 KB
• Volume: 38
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570380337

✦ Synopsis

Abstract

The stereoselective rearrangement of tetrahydrofuran or tetrahydropyran rings having a phenylsulfanyl group in an exo position, via the intermediate thiiranium ions, is reported. The 5‐ or 6‐exo‐tet cyclization of hydroxy sulfides gave the kinetic products while the 6‐endo‐tet or 5‐endo‐tet gave the thermodynamic products. The rearrangement of the 5‐exo product to the 6‐endo‐ one is an interesting way for the stereoselective synthesis of substituted tetrahydropyrans.