R(2)AlCl-coordinated N-methacryloylsultam Ic undergoes efficient, endo-selective and highly diastereoface controlled [4+2]-additions to cyclopentadiene, isoprene, (E)-piperylene and the 2-silyloxydienes 10 and 12. The resulting crystalline cycloadducts are smoothly reduced with LiAlH4 providing the recovered auxiliary and the corresponding enantiomerically pure alcohols.