L-Proline-Catalyzed Intramolecular Cyclization of 5-Hydroxypentene to β-Halogenated Tetrahydrofuran.

Abstract A series of β-bromo- and β-iodotetrahydrofurans was synthesized from the reaction mixture of 5-hydroxypentene, l -proline, NBS (or I 2 ) in THF at 0 °C for 10 min. This l -proline-catalyzed intramolecular cyclization provides a simple and efficient method for the preparation of β-halogenated tetrahydrofuran.