Asymmetric Catalytic [3+2] Annulation of Donor-Acceptor Cyclopropane with Cyclic Ketones: Facile Access to Enantioenriched 1-Oxaspiro[4.5]decanes^†

A copper catalyzed enantioselective [3+2] annulation of donor-acceptor cyclopropanes with cyclic ketones has been developed, providing a concise protocol to enantioenriched 1-oxaspiro[4.5]decanes in up to 98% yield with up to >99/1 dr and up to 92% ee. In addition, this method also provides a facile access to the enantioselective desymmetrisation of various 4-substituted cyclohexanones. The resulting products were easily converted to the core structures of two natural products Heliespirones A and halogenated sesquiterpene isolated from L. saitoi.