We established a highly enantioselective Si-H insertion reaction to construct chiral centers at the carbon and silicon atoms, using a Ru(ii)-pheox catalyst. The catalytic asymmetric Si-H insertion reaction of α-methyl-α-diazoesters proceeded smoothly with excellent stereoinduction at both the neighboring carbon and silicon atoms (up to 99% yield and 99% ee).

The first highly enantioselective intramolecular cyclopropanation of electron-deficient olefins, in the presence of Ru(II)--Pheox catalyst, is reported. The corresponding cyclopropane-fused γ-lactones were obtained in high yields (up to 99%) with excellent enantioselectivities (ee up to 99%). Moreover, this method enables efficient access to enantioenriched dicarbonyl cyclopropane derivatives, which are important intermediates for the synthesis of various bioactive compounds.

We have established a method for the highly regio- and enantioselective functionalization of tert-butyl groups via intramolecular amide carbene insertion into C–H bonds, yielding γ-lactams with 91% ee in up to 99% yield. This reaction uses a ruthenium­(II) phenyl oxazoline (Ru­(II)-Pheox) complex. The catalytic intramolecular carbene transfer reaction to the primary C–H bond proceeds rapidly and selectively compared to that with secondary C–H, benzylic secondary C–H, tert-C–H, or sp2C–H bonds in the presence of 1 mol % Ru­(II)-Pheox catalyst. This is the first example of a catalytic carbenoid insertion into an unactivated tert-butyl group with enantiocontrol at the carbenoid carbon.

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions was performed using density functional theory (DFT). In this study, cyclopropane ring–fused γ‐lactones, which are 5.8 kcal/mol more stable than the corresponding minor enantiomer, are obtained as the major product. The results of the calculations suggest that the enantioselectivity of the Ru(II)‐Pheox–catalyzed intramolecular cyclopropanation reaction is affected by the energy differences between the starting structures 5l and 5i. The reaction pathway was found to be a stepwise mechanism that proceeds through the formation of a metallacyclobutane intermediate. This is the first example of a computational chemical analysis of enantioselective control in an intramolecular carbene‐transfer reaction using C1‐symmetric catalysts.

Optically active spirocyclopropyloxindole derivatives were efficiently synthesized from diazooxindoles and olefins in the presence of a Ru(ii)-Pheox catalyst.