A highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by chiral Ru(II)–Pheox complexes was developed to give chiral cyclopropyl sulfones in high yields (up to 99%) with excellent trans-selectivity and enantioselectivity (up to 98% ee).

A highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by chiral Ru(II)–Pheox complexes was developed to give chiral cyclopropyl sulfones in high yields (up to 99%) with excellent trans-selectivity and enantioselectivity (up to 98% ee).

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).

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).

AbstractInter- and intramolecular cyclopropanations of a series of diazo Weinreb amides and trans-allylic diazo Weinreb amide derivatives have been achieved using chiral ruthenium(II)-Amm-Pheox catalyst to give the corresponding chiral cyclopropyl Weinreb amides in excellent yield (up to 99%) with excellent enantioselectivity (up to 99% ee). The chiral products could easily undergo useful synthetic transformations to give the corresponding aldehydes, alcohols and ketones in high yields and enantioselectivities.

The transition-metal-catalyzed asymmetric cyclopropanation of olefins with diazoacetates has become one of the most important methods for the synthesis of optically active cyclopropane derivatives, which are key pharmaceutical building blocks and present in a large number of natural products. To date, significant progress has been made in this area of research, and efficient stereocontrolled synthetic approaches to cyclopropane derivatives have been developed using rhodium, ruthenium, copper, and cobalt catalysts. However, the vast majority of these strategies are limited to electron-rich olefins, such as styrene derivatives, due to the electrophilicity of the metal–carbene intermediates generated from the reaction of the metal with the diazo compound. Recently, the D2-symmetric Co(II)–phophyrin complexes developed by Zhang et al. were shown to be the most efficient catalysts for the asymmetric cyclopropanation of electron-deficient olefins. This catalytic system is mechanistically distinct from the previous rhodium and copper catalytic systems, proceeding via radical intermediates. However, the asymmetric cyclopropanation of vinyl carbamates, allenes, and α,β-unsaturated carbonyl compounds has rarely been reported. Therefore, the development of new powerful catalysts for the asymmetric cyclopropanation of a wide range of olefinic substrates is the next challenge in this field.In this Account, we summarize our recent studies on the Ru(II)–Pheox-catalyzed asymmetric cyclopropanation of various olefins, including vinyl carbamates, allenes, and α,β-unsaturated carbonyl compounds. We demonstrate that the developed catalytic system effectively promotes the asymmetric cyclopropanation of a wide variety of olefins to produce the desired cyclopropane products in high yields with excellent stereocontrol. The use of succinimidyl-, ketone-, and ester-functionalized diazoacetates as carbene sources was found to be crucial for the high stereoselectivity of the cyclopropanation reactions. In addition, we describe reusable chiral Ru(II)–Pheox catalysts, namely, water-soluble Ru(II)–hm-Pheox and polymer-supported PS-Ru(II)–Pheox, which can be reused at least five times in inter- and intramolecular cyclopropanation reactions without any significant loss of catalytic activity or enantioselectivity. These Ru(II)–Pheox-catalyzed asymmetric cyclopropanation reactions provide an elegant method to access a series of optically active cyclopropane derivatives, including cyclopropylamines, dicarbonyl cyclopropanes, alkylidenecyclopropanes, and cyclopropane-fused γ-lactones, which are intermediates in the syntheses of various biologically active compounds.The novel chiral Ru(II)–Pheox complexes are readily synthesized in high yield from inexpensive, commercially available benzoyl chloride and amino alcohols, then fully characterized using X-ray diffraction analysis, NMR, and elemental analysis. These catalysts are easy to handle and stable under ordinary temperatures and conditions and can be used after three months of storage without any loss of catalytic activity or stereoselectivity.

The first highly stereoselective cyclopropanation of diazo Weinreb amides with olefins was accomplished using chiral Ru(II)–Amm–Pheox complex 7a to give the corresponding chiral cyclopropyl Weinreb amides in high yields (up to 99%) with excellent diastereoselectivities (up to 99:1 dr) and enantioselectivities (up to 96% 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.

Ru(II)-Pheox-catalyzed asymmetric cyclopropanation of diethyl diazomethylphosphonate with alkenes, including α,β-unsaturated carbonyl compounds, afforded the corresponding optically active cyclopropylphosphonates in high yields and with excellent diastereoselectivity (up to 99:1) and enantioselectivity (up to 99% ee).

An efficient protocol for the synthesis of optically active alkylidenecyclopropanes (ACPs) via the Ru(II)-Pheox catalyzed asymmetric cyclopropanation of allenes has been established. This catalytic system proceeded with high regioselectivity to give the ACP products in high yield with high diastereoselectivity (up to 99/1) and enantioselectivity (up to 99% ee).

The Ru(II)-Pheox-catalyzed asymmetric cyclopropanation of vinylcarbamates with diazoesters resulted in the corresponding cyclopropylamine derivatives in high yield and excellent diastereoselectivity (up to 96:4) and enantioselectivity (up to 99% ee).

The Ru(II)–Pheox complex is an efficient catalyst for the intermolecular cyclopropanation of various terminal olefins with succinimidyl diazoacetate. This catalytic system can perform under mild conditions, and the desired cyclopropane products are obtained in high yields with excellent diastereoselectivity and enantioselectivity.

The Ru(II)–Pheox complex is an efficient catalyst for the intermolecular cyclopropanation of various terminal olefins with succinimidyl diazoacetate. This catalytic system can perform under mild conditions, and the desired cyclopropane products are obtained in high yields with excellent diastereoselectivity and enantioselectivity.

The first highly stereoselective cyclopropanation of diazo Weinreb amides with olefins was accomplished using chiral Ru(II)–Amm–Pheox complex 7a to give the corresponding chiral cyclopropyl Weinreb amides in high yields (up to 99%) with excellent diastereoselectivities (up to 99:1 dr) and enantioselectivities (up to 96% ee).

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).

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).