An Efficient and Highly Enantio- and Diastereoselective Cyclopropanation of Olefins Catalyzed by Schiff-Base Ruthenium(II) Complexes We thank the reviewers for their helpful comments. Support from the DuPont Company and the Beckman, Dreyfus, and Packard Foundations are gratefully acknowledged. S.T.N. is an Alfred P. Sloan Fellow.

Both electron-rich and electron-deficient olefins—such as styrene and methyl methacrylate—undergo efficient (yields >90 %) cyclopropanation with ethyl diazoa...