SUBSTITUENT EFFECTS ON THE REGIOCHEMICAL AND STEREOCHEMICAL COURSE OF THE NUSSBAUMER-FRATER VARIATION OF THE PRINS CYCLIZATION

摘要

Eleven vinylogous carbonates were examined in the Nussbaumer-Frater variation of the Prins cyclization to provide 2,3,4,6-tetrasubstituted tetrahydropyrans. Results indicate that substrate olefin geometry is a more reliable control element than preset substrate vicinal stereochemistry for establishing C2-C3 vicinal stereochemistry in tetrahydropyran products.