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A method for the synthesis of natural lignan lactones was developed by utilizing chiral dirhodium(II) carboxamidate catalysts. The synthetic process is characterized by C-H insertion which was initiated by the overlap of the carbon p-orbital and sigma-orbital of the metal carbene and the reacting C-H bond. The formation of beta-substituted-gamma-butyrolactones was initiated by the reaction of chiral Rh2(MPPIM)4 catalysts to fully aliphatic systems.

A method for the synthesis of natural lignan lactones was developed by utilizing chiral dirhodium(II) carboxamidate catalysts. The synthetic process is characterized by C-H insertion which was initiated by the overlap of the carbon p-orbital and sigma-orbital of the metal carbene and the reacting C-H bond. The formation of beta-substituted-gamma-butyrolactones was initiated by the reaction of chiral Rh2(MPPIM)4 catalysts to fully aliphatic systems.

The five dirhodium(II) tetracarboxamidates derived from chiral methyl 1-acyl-2-oxoimidazolidine-4(S)-carboxylates each has unique capabilities as a chiral catalyst for highly stereoselective metal carbene transformations. Monoclinic crystals in space group P2(sub 1) are formed by the simplest member of the series, (2,2-cis)-dirhodium(II) tetrakis(methyl 1-acyl-2-oxoimidazolidine-4(S)-carboxylate), (2,2-cis)-Rh2(4S-MACIM)4. Four of them have been prepared by ligand substitution with dirhodium(II) acetate.

The feasibility of using chiral dirhodium(II) tetrakis(methyl 2-pyrrolidone-5 S-carboxylate), Rh2(5S-MEPY)4 and its enantiomer, Rh2(5R-MEPY)4, as catalysts for the intramolecular cyclopropanations of allylic and homoallylic diazoacetates and diazoacetamides was evaluated. Results showed that the use of the chiral dirhodium(II) catalysts produced cyclopropanes with excellent enantioselectivity.

A new, efficient carbon-hydrogen insertion methodology is used for the highly enantio- and regioselective syntheses of natural dibenzylbutyrolactone lignans from 3-aryl-1-propyl diazoacetates using chiral oxoimidazolidine carboxylate-ligated dirhodium(II) catalysts. The dirhodium catalysts are prepared from m-1-(3-phenylpropanoyl)-2-oxoimidazolidine-4(S)-carboxylate and its 4(R) enantiomer. The openness in the area around the rhodium catalyst, Rh2(4-R-MPPIM)4 allows insertion of the C-H bond.

Carbon–heteroatom bonds (C–X) are ubiquitous and are among the most reactive components of organic compounds. Therefore investigations of the construction of C–X bonds are fundamental and vibrant fields in organic chemistry. Transition-metal-catalyzed heteroatom–hydrogen bond (X–H) insertions via a metal carbene or carbenoid intermediate represent one of the most efficient approaches to form C–X bonds. Because of the availability of substrates, neutral and mild reaction conditions, and high reactivity of these transformations, researchers have widely applied transition-metal-catalyzed X–H insertions in organic synthesis. Researchers have developed a variety of rhodium-catalyzed asymmetric C–H insertion reactions with high to excellent enantioselectivities for a wide range of substrates. However, at the time that we launched our research, very few highly enantioselective X–H insertions had been documented primarily because of a lack of efficient chiral catalysts and indistinct insertion mechanisms. [ABSTRACT FROM AUTHOR]

Stereoconvergent reactions enable the transformation of mixed stereoisomers into well-defined, chiral products─a crucial strategy for handling Z / E -mixed olefins, which are common but challenging substrates in organic synthesis. Herein, we report a stereoconvergent and highly enantioselective method for synthesizing Z -homoallylic alcohols via the nickel-catalyzed reductive coupling of Z / E -mixed 1,3-dienes with aldehydes. This process is enabled by an N -heterocyclic carbene ligand characterized by C 2 -symmetric backbone chirality and bulky 2,6-diisopropyl N -aryl substituents. Our method achieves excellent stereocontrol over both enantioselectivity and Z -selectivity in a single step, producing chiral Z -homoallylic alcohols that are valuable in natural products and pharmaceuticals.

We present the first enantioselective nickel-catalyzed borylative coupling of 1,3-dienes with aldehydes, providing an efficient route to highly valuable homoallylic alcohols in a single step. The reaction involves the 1,4-carboboration of dienes, leading to the formation of C-C and C-B bonds accompanied by the construction of two continuous stereogenic centers. Enabled by a chiral spiro phosphine-oxazoline nickel complex, this transformation yields products with exceptional diastereoselectivity, E -selectivity, and enantioselectivity. The diastereoselectivity of the reaction can be controlled by employing either ( Z )-1,3-dienes or ( E )-1,3-dienes.

Herein, we report the first enantioselective total synthesis of the highly complex hamigeran diterpenoid (-)-hamigeran F and its rearrangement product. The synthetic strategy features key steps of asymmetric hydrogenation, Horner-Wadsworth-Emmons olefination, and intramolecular Friedel-Crafts acylation to construct the [6,6,5]-tricyclic skeleton bearing three consecutive stereocenters, a sequence of steps involving Rosenmund reduction, Wittig reaction, dihydroxylation to assemble the α-acetoxy ketone group, and an intramolecular aldol reaction to build the tetracyclic core structure.

Herein, we describe a novel protocol for visible-light-induced α,γ-C(sp 3 )-H difunctionalization of piperidines. This redox-neutral, atom-economical protocol, which exhibits a broad substrate scope and good functional group compatibility, constitutes a concise, practical method for constructing piperidine-containing bridged-ring molecules. Preliminary mechanistic studies indicated that highly regioselective activation of the inert γ-C(sp 3 )-H bond of piperidines was achieved through a 1,5-hydrogen atom transfer reaction of a nitrogen radical generated in situ.

A three-step process for the enantioselective assembly of cis -fused octahydrophenanthrenes with a quaternary stereocenter is reported. This synthetic strategy relies on a regioselective γ-alkylation, a one-pot sequence of asymmetric hydrogenation and oxidation, and an intramolecular enolate arylation to facilitate the rapid and enantioselective construction of cis -fused octahydrophenanthrene scaffolds with an arylated all-carbon quaternary stereocenter concisely and efficiently.

An efficient asymmetric hydrogenation of racemic α-aryl-β-ethoxycarbonyl cyclopentanones via dynamic kinetic resolution is reported. Via catalysis by a chiral iridium Ir-SpiroPAP catalyst, a range of racemic α-aryl-β-ethoxycarbonyl cyclopentanones were hydrogenated to the corresponding ester-functionalized chiral 2-arylcyclopentanols with three contiguous stereocenters in high yields with excellent enantio- and diastereoselectivities. This method was successfully applied in the enantioselective synthesis of cyclopentane-based γ-amino ester/alcohol derivatives and phenylpropanoid (+)-burmaniol A.

A highly enantioselective Si-H bond insertion reaction of α-aryldiazoacetates catalyzed by chiral spiro dirhodium tetraphosphate was developed. Various chiral α-silyl esters were prepared with high yield (up to 92%) and excellent enantioselectivity (up to >99% ee) through this protocol. It is noteworthy that the 2-substituted aryl diazoacetates, which are challenging substrates for other chiral dirhodium catalysts, also exhibited good results in this reaction. This work represents one of the few successful applications of chiral dirhodium phosphates in asymmetric catalysis.

An efficient asymmetric hydrogenation of racemic γ-substituted cyclic β-ketoesters via dynamic kinetic resolution to provide chiral cyclic β-hydroxy esters with three contiguous stereocenters is reported. Using a chiral spiro iridium catalyst ( R )- 5 (Ir-SpiroSAP), a series of racemic γ-aryl/alkyl substituted cyclic β-ketoesters were hydrogenated to the corresponding chiral cyclic β-hydroxy esters in high yields (84-97%) with good to excellent enantioselectivities (69->99% ee) and cis , cis -selectivities (up to >99:1).

The Nazarov electrocyclization reaction is a convenient, widely used method for construction of cyclopentenones. In the past few decades, catalytic asymmetric versions of the reaction have been extensively studied, but the strategies used to control the position of the double bond limit the substituent pattern of the products and thus the synthetic applications of the reaction. Herein, we report highly enantioselective silicon-directed Nazarov reactions which were cooperatively catalyzed by a Lewis acid and a chiral Brønsted acid. The chiral cyclopentenones we synthesized using this method generally cannot be obtained by means of other catalytic enantioselective reactions, including previously reported methods for enantioselective Nazarov cyclization. The silicon group in the dienone substrate stabilized the β-carbocation of the intermediate, thereby determining the position of the double bond in the product. Mechanistic studies suggested that the combination of Lewis and Brønsted acids synergistically activated the dienone substrate and that the enantioselectivity of the reaction originated from a chiral Brønsted acid promoted proton transfer reaction of the enol intermediate.

A protocol of iridium catalyzed asymmetric hydrogenation of 4-alkyl substituted 3-ethoxycarbonyl quinolin-2-ones and coumarins has been reported, providing a wide range of chiral dihydroquinolin-2-ones and dihydrocoumarins in high yields with excellent enantioselectivities (up to 99% ee) and high turnover numbers (up to 28 000). This efficient protocol was successfully applied for the synthesis of MPR3160 and the key chiral intermediate of R-106578.

Chiral propargylsilanes and chiral allenylsilanes have emerged as versatile building blocks for organic synthesis. However, efficient methods for preparing these organosilicon compounds are lacking. We herein report a highly enantioselective method for synthesis of chiral propargylsilanes and chiral allenylsilanes from readily available alkynyl sulfonylhydrazones. Specifically, chiral spiro phosphate dirhodium complexes were used to catalyze asymmetric insertion of alkynyl carbenes into the Si-H bonds of silanes to afford a variety of chiral propargylsilanes with excellent enantioselectivity. Subsequently, a platinum catalyst was used for stereospecific isomerization of the chiral propargylsilanes to the corresponding chiral allenylsilanes.

Herein, we report a practical method for efficient asymmetric hydrogenation of β-aryl alkylidene malonates. With a site-specifically tailored chiral spiro iridium catalyst, a series of β-aryl alkylidene malonate esters were hydrogenated to afford chiral malonate esters with good to excellent enantioselectivities (up to 99% ee) and high turnover numbers (up to 19000). The results showed that installing an ester group in α,β-unsaturated carboxylic esters significantly increased the efficiency of their asymmetric hydrogenation reactions.