Asymmetric H2O-Nucleophilic Ring Opening of D-A Cyclopropanes: Catalyst Serves as a Source of Water.

The first catalytic enantioselective ring-opening reaction of donor-acceptor cyclopropanes with water is described. By employing Cy-TOX/Cu(II) as catalyst, the reaction performed very well over a broad range of substrates, leading to the ring-opening products in 70-96% yields with up to 95% ee under mild conditions. The current method provides a new approach to direct access to γ-substituted GBH derivatives very efficiently. Importantly, Cu(ClO4)2·6H2O proves to serve as both a Lewis acid and a source of water, which affords a fine system to controllably release water as a nucleophile in the asymmetric catalysis.