Regioselective epoxide ring opening. Steroselective synthesis of a tetrahydropyran ring

The stereoselective synthesis of a 2substituted tetrahydropyran with adjacent alkoxybearing stereogenic centre is described. The key steps of this synthesis were the stereoselective epoxidation of an allylic alcohol and the regioselective epoxide ring opening by lithium aluminum hydride. The regio and stereoselective synthesis of a trihydroxyselenide and a trihydroxysulfide is also described. The latter compounds are not suitable for cyclization to tetrahydrofuran ring.