Catalytic Asymmetric Iodocarbocyclization Reaction of 4-Alkenylmalonates and Its Application to Enantiotopic Group Selective Reaction.

The iodocarbocyclization reaction of 4-alkenylmalonate derivatives proceeded with excellent enantioselectivity (>/=95% ee) in the presence of 10-40 mol % of Ti(TADDOLate)(2). The Ti(TADDOLate)(2)-mediated catalytic asymmetric reaction was extended to the enantiotopic group selective reaction of bisalkenylated malonates, giving rise to trisubstituted cyclopentanoid compounds with both high diastereoselectivity (86-94% de) and excellent enantioselectivity (>/=95% ee). An efficient synthesis of (+)-boschnialactone from the product of the present reaction was also achieved.