Abstract
(Equation presented) A novel In(OTf) 3 -catalyzed (3,5) oxonium-ene type cyclization for the facile construction of various multisubstituted tetrahydrofurans and tetrahydropyrans was successfully developed. Further mechanistic investigations unveiled an In(OTf) 3 -catalyzed skeletal reorganization of the tetrahydrofuran to its thermodynamic isomer under thermal conditions.