l-Proline-catalyzed intramolecular cyclization of 5-hydroxypentene to β-halogenated tetrahydrofuran

A series of β-bromo- and β-iodotetrahydrofurans was synthesized from the reaction mixture of 5-hydroxypentene, l-proline, NBS (or I2) 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.