Experimental and Computational Studies for the Synthesis of Functionalized Cyclopropanes from 2‐Substituted Allylic Derivatives with Ethyl Diazoacetate.

The catalytic asymmetric synthesis of highly functionalized cyclopropanes from 2‐substituted allylic derivatives is reported. Using ethyl diazo acetate, the reaction, catalyzed by a chiral ruthenium complex (Ru(II)‐Pheox), furnished the corresponding easily separable cis and trans cyclopropanes in moderate to high yields (32‐97 %) and excellent ee (86‐99 %). This approach significantly extends the portfolio of accessible enantioenriched cyclopropanes from an underexplored class of olefins. DFT calculations suggest that an outer‐sphere mechanism is operative in this system. [ABSTRACT FROM AUTHOR]