Stereoselective Cyclisations to Form Tetrahydropyrans

16 May 2005

Cyclisation of homoallylic ethers with aldehydes under strong acid conditions is known as the Prins cyclisation and leads to tetrahydropyrans with a heteroatom on the 4 position. By choice of Lewis acid, some control over whether the heteroatom is axial or equatorial can be achieved (Jasti R et al, J Am Chem Soc, 2004, 126, 9904).