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A Cu‐catalyzed asymmetric synthesis of silicon‐stereogenic benzoxasiloles has been realized via intramolecular Si−O coupling of [2‐(hydroxymethyl)phenyl]silanes. Cu(I)/difluorphos is found to be an efficient catalytic system for enantioselective Si−C bond cleavage and Si−O bond formation. In addition, kinetic resolution of racemic substituted [2‐(hydroxymethyl)phenyl]silanes using Cu(I)/ PyrOx (pyridine‐oxazoline ligands) as the catalytic system is developed to afford carbon‐ and silicon‐stereogenic benzoxasiloles. Ring‐opening reactions of chiral benzoxasiloles with organolithiums and Grignard reagents yield various enantioenriched functionalized tetraorganosilanes. [ABSTRACT FROM AUTHOR]

Strategies on the construction of enantiomerically pure silicon‐stereogenic silanes generally relies on desymmetrization of prochiral and symmetric substrates. However, dynamic kinetic asymmetric transformations of organosilicon compounds have remained underdeveloped and unforeseen owing to a lack of an effective method for deracemization of the static silicon stereocenters. Here we report the first Rh‐catalyzed dynamic kinetic asymmetric intramolecular hydrosilylation (DyKAH) with "silicon‐centered" racemic hydrosilanes that enables the facile preparation of silicon‐stereogenic benzosiloles in good yields and excellent enantioselectivities. The special rhodium catalyst controlled by non‐diastereopure‐type mixed phosphine‐phosphoramidite ligand with axial chirality and multiple stereocenters can induce enantioselectivity efficiently in this novel DyKAH reaction. Density functional theory (DFT) calculations suggest that the amide moiety in chiral ligand plays important role in facilitating the SN2 substitution of chloride ion to realize the chiral inversion of silicon center. [ABSTRACT FROM AUTHOR]

A palladium‐catalyzed enantioselective intramolecular σ‐bond cross‐exchange between C−I and C−C bonds is realized, providing chiral indanones bearing an alkyl iodide group and an all‐carbon quaternary stereocenter. Pd/TADDOL‐derived phosphoramidite is found to be an efficient catalytic system for both C−C bond cleavage and alkyl iodide reductive elimination. In addition to aryl iodides, aryl bromides can also be used for this transformation in the presence of KI. Density‐functional theory (DFT) calculation studies support the ring‐opening of cyclobutanones occuring through an oxidative addition/reductive elimination process involving PdIV species. [ABSTRACT FROM AUTHOR]

A palladium‐catalyzed enantioselective sequential ring‐opening/cross‐coupling of cyclobutanones is disclosed that provides chiral indanones bearing C3‐quaternary stereocenters. The reaction process involves palladium‐catalyzed nucleophilic addition of cyclobutanones and aryl halides, enantioselective β‐carbon elimination, and intermolecular trapping of a transient σ‐alkylpalladium complex with boronic acids. Alternatively, an intramolecular cyclopropanation is realized through C−H bond functionalization in the absence of external coupling reagents, affording chiral cyclopropane‐fused‐indanones in good yields and enantioselectivity. Enantioselective desymmetrization of prochiral cyclobutanones was realized through tandem palladium‐catalyzed ring‐opening/cyclopropanation to provide chiral cyclopropane‐fused indanones. With external coupling reagents, the transient σ‐alkylpalladium intermediate can be captured to afford an array of chiral indanones bearing C3‐quaternary stereocenters. [ABSTRACT FROM AUTHOR]

Abstract: The use of chiral ligands to tune the reactivity and enantioselectivity of transition‐metal catalyst for asymmetric transformations is a central challenge in synthetic organic chemistry. In this manuscript, chiral P‐ligand (Tao‐Phos)‐assisted Cu2O‐nanoparticles‐catalyzed asymmetric azide–alkyne Huisgen cycloaddition is reported. The unique features of Tao‐Phos were determined in the copper‐catalyzed desymmetrization of pyrazolone‐derived bisalkynes through catalytic asymmetric Huisgen [3+2] cycloaddition (CAHC). This CAHC transformation resulted in good yields with moderate to high enantioselectivities. [ABSTRACT FROM AUTHOR]

Enantioselective synthesis of chiral heterocyclic derivatives is an important and challenging topic in the field of synthetic chemistry. In this work, the first stereocontrolled dimerization-type homo-1,3-dipolar [3+2] cycloaddition reaction of glycine aldimino esters for creating new heterocycles bearing multiple stereogenic centers has been developed through chiral phosphine ligand-involved silver catalysis. A variety of chiral imidazolidines could be obtained with high yields and good diastereoselectivities as well as excellent enantioselectivities by employing Xing-Phos as chiral phosphorus ligand. In addition, the silver/Xing-Phos-catalyzed homo-1,3-dipolar [3+2] cycloaddition reaction is also a facile and novel protocol for catalytic polymerization of bifunctional glycine aldimino esters to give chiral poly(imidazolidine)s with a very narrow molecular weight distribution. [ABSTRACT FROM AUTHOR]

The mechanism-oriented reaction design for the divergent synthesis of chiral molecules from simple starting materials is highly desirable. In this work, aromatic amide-derived nonbiarylatropisomer/silver (silver/Xing-Phos) complex was used to catalyze the Michael addition of glycine aldimino esters to chalcones and successfully applied to the subsequent cyclocondensation to afford substituted cis-Δ(1)-pyrroline derivatives with up to 98 % ee. Besides the inherent performance of the chiral Ag/Xing-Phos catalyst system, it was found that the workup of such reactions played an important role for the stereoselective construction of stereodivergent Δ(1)-pyrrolines, in which an epimerization of the cis-Δ(1)-pyrrolines to the trans-isomers during was revealed. [ABSTRACT FROM AUTHOR]

New Schiff bases derived from chiral d -camphor were determined to be effective phosphine ligands for the asymmetric palladium-catalyzed allylic alkylation of activated methylene compounds, the allylic etherification of alcohols, and the allylic amination of primary amines or secondary amines, in which the corresponding products with various functional groups were achieved in good yields with excellent enantioselectivities (up to >99 % ee). Remarkably, the palladium catalyst derived from Schiff base L2 afforded the highest level of enantioselectivity reported to date for allylic substitution reactions, including allylic etherification and allylic amination, which revealed the privileged role of d-camphor-derived Schiff bases in palladium-catalyzed allylic substitution reactions. [ABSTRACT FROM AUTHOR]

Recently, academic chemists have renewed their interest in the development of 1,1′-binaphthalene-2,2′-diol ( BINOL)-derived chiral ligands. Six years ago, a working hypothesis, that the chirality matching of hybrid chirality on a ligand could probably lead to high levels of stereoselective induction, prompted us to use the axial chirality of BINOL derivatives to generate new stereogenic centers within the same molecule with high stereoselectivity, obtaining as a result sterically favorable ligands for applications in asymmetric catalysis. This Personal Account describes our laboratory's efforts toward the development of a novel class of BINOL-derived atropisomers bearing both axial and sp3 central chirality, the so-called Ar- BINMOLs, for asymmetric synthesis. Furthermore, on the basis of the successful application of Ar- BINMOLs and their derivatives in asymmetric catalysis, the search for highly efficient and enantioselective processes also compelled us to give special attention to the BINOL-derived multifunctional ligands with multiple stereogenic centers for use in catalytic asymmetric reactions. [ABSTRACT FROM AUTHOR]

In recent years, remarkable progress has been made in the enantioselective silylation of alcohols. Owing to the successful site- and stereoselective functionalization of hydroxy groups, silyl ether formations have evolved from being a simple reaction for functional-group protection into a powerful enantioselective process. In this Minireview, we highlight important recent findings in this emerging field. [ABSTRACT FROM AUTHOR]

The synthesis of a series of aromatic amide-derived non-biaryl atropisomers with a phosphine group and multiple stereogenic centers is reported. The novel phosphine ligands exhibit high diastereo- and enantioselectivities (up to >99:1 d.r., 95-99 % ee) as well as yields in the silver-catalyzed asymmetric [3+2] cycloaddition of aldiminoesters with nitroalkenes, which provides a highly enantioselective strategy for the synthesis of optically pure nitro-substituted pyrrolidines. In addition, the experimental results with regard to the carbon stereogenic center as well as the amide stereochemistry confirmed the potential of hemilabile atropisomers as chiral ligand in catalytic asymmetric [3+2] cycloaddition reaction. [ABSTRACT FROM AUTHOR]

A copper catalyst system derived from TaoPhos and CuF2 was used successfully for catalytic asymmetric Huisgen [3+2] cycloaddition of azides and alkynes to give optically pure products containing succinimide- and triazole-substituted quaternary carbon stereogenic centers. The desired products were obtained in good yields (60-80 %) and 85:15 to >99:1 enantiomeric ratio (e.r.) in this click cycloaddition reaction. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed allylic alkylation of unsubstituted 2-cyanoacetates using a 1,1′-bi-2-naphthol-derived multifunctional N,O,P ligand is reported. A number of chiral monosubstituted 2-cyanoacetates with two adjacent stereogenic carbon centers are obtained in this Pd-catalyzed asymmetric allylic alkylation reaction, in which the multistereogenic and multifunctional 1,1′-bi-2-naphthol-derived N,O,P ligand-promoted Pd-catalyzed asymmetric allylic alkylation reaction proceeds smoothly in high diastereo- and enantioselectivity (up to >99:1 dr and up to 96 % ee). [ABSTRACT FROM AUTHOR]

A facile and powerful enantioselective construction of CF containing molecules was successfully developed through asymmetric fluorination of β-ketoamides catalyzed by Ar-BINMOL-derived salan-CuII system (Ar-BINMOL=1,1′-Binaphthalene-2-α-arylmethanol-2′-ol, Cu = copper). The present catalytic system exhibited excellent enantioselectivity and a broad substrate scope for indanone-derived β-ketoamides under mild conditions (up to 99 % ee and 99 % yields). Notably, the biomimetic salan-copper complex was demonstrated for the first time to be a highly efficient catalyst in the fluorination of β-ketoamides. Experimental results and mechanistic studies indicated that both excess amount of copper salt and electrophilic attack of cationic fluorine to activated methylene assisted by amide group on the β-ketoamides were key factors for high yield and excellent enantioselectivity, respectively, in this enantioselective fluorination, which was controlled by the two-point binding between the salan-copper complex with cyclic β-ketoamides and hydrogen-bonding activation of the electrophilic fluorinating reagent. [ABSTRACT FROM AUTHOR]

An interesting group of multifunctional phosphines (Ar-BINMOL-Phos; Ar-BINMOL=1,1′-binaphthalene-2-α-arylmethanol-2′-ol) with multi-stereogenic centers of axial and sp3-central chirality has been prepared successfully from a single chiral source through a concise synthetic route, in which the neighbouring lithium-promoted [1,2]-Wittig rearrangement proceeding with excellent diastereoselectivity and enantioselectivity is the key process in this approach. Also, in the catalytic alkynylation of aromatic aldehydes with terminal alkynes, the combination of these Ar-BINMOL-Phos ligands with dimethylzinc was found to be an effective catalyst system to afford predominantly the S-configured propargylic alcohols, whereas the additional use of calcium hydride and n-butyllithium along with the same Ar-BINMOL-Phos ligands gave the R-configured products in high yields and excellent enantioselectivities (up to >99% ee). [ABSTRACT FROM AUTHOR]

A series of silicon-containing diols are synthesized and used in lipase-catalyzed remote desymmetrization. This synthetic method is valuable in the construction of optically active silicon-stereogenic organosilicon compounds. Good enantioselectivities of the remote desymmetrization was achieved with Candida antarctica lipase B (CAL-B) (up to 90:10 er). [ABSTRACT FROM AUTHOR]

CycloN2P2‐Phos! The use of the multidentate phosphine, CycloN2P2‐Phos (see graphic), which contains four heteroatoms (two nitrogen and two phosphorus atoms), in the palladium‐catalyzed asymmetric allylic etherification (AAE) of alcohols and silanols leads to excellent levels of enantioselectivity (up to 99 % ee). [ABSTRACT FROM AUTHOR]

This minireview focuses on the recent advances in the synthetic application of amino acid-derived bifunctional phosphine catalysts bearing a hydrogen-bond donor. In the examples illustrated, the amino acid-based phosphines have already been proven to be versatile, catalyzing a wide range of asymmetric reactions, including (aza)-MBH reactions, [3+2] cyclizations, [4+2] cycloadditions, allylic alkylation, and Michael addition. [ABSTRACT FROM AUTHOR]

In this work, we have successfully synthesized a new family of chiral Schiff base-phosphine ligands derived from chiral binaphthol (BINOL) and chiral primary amine. The controllable synthesis of a novel hexadentate and tetradentate N,O,P ligand that contains both axial and sp3-central chirality from axial BINOL and sp3-central primary amine led to the establishment of an efficient multifunctional N,O,P ligand for copper-catalyzed of an organozinc reagent. In the asymmetric conjugate reaction of organozinc reagents to enones, the polymer-like bimetallic multinuclear CuZn complex constructed in situ was found to be substrate-selective and a highly excellent catalyst for diethylzinc reagents in terms of (up to >99 % ee). More importantly, the chirality matching between different chiral sources, C2-axial binaphthol and sp3-central chiral phosphine, was crucial to the induction in this reaction. The experimental results indicated that our chiral ligand ( R, S, S)- L1- and ( R, S)- L4-based bimetallic complex catalyst system exhibited the highest catalytic performance to date in terms of and conversion even in the presence of 0.005 mol % of catalyst (S/C=20 000, turnover number (TON)=17 600). We also studied the tandem or of enantiomerically enriched zinc enolates that formed in situ from copper- L4-complex-catalyzed , which resulted in the high-yield synthesis of chiral silyl enol ethers and enoacetates, respectively. Furthermore, the specialized structure of the present multifunctional N,O,P ligand L1 or L4, and the corresponding mechanistic study of the copper catalyst system were investigated by 31P NMR spectroscopy, circular dichroism (CD), and UV/Vis absorption. [ABSTRACT FROM AUTHOR]

The direct asymmetric aldol reaction catalyzed by the simple and commercially available chiral primary diamines, (1S,2S)-1,2-diphenylethane-1,2-diamine and (1R,2R)-1,2-diphenylethane-1,2-diamine, is presented. The catalyst system is a primary amine with Brønsted acid-catalyzed direct aldol reaction of p-nitrobenzaldehyde and cyclohexanone with high chemo- and stereoselectivity on water, which furnishes the corresponding β-hydroxyketone with up to 94% ee. [ABSTRACT FROM AUTHOR]

Chiral Si-, P-, and S-containing organic compounds with central, planar, and axial chiralities have found a plethora of applications in various fields of chemistry. Despite significant efforts to explore new catalytic methodologies and synthetic applications to access such compounds, there are still only a few examples which are low in number and limited in diversity. The catalytic construction of Si-, P-, and S-stereogenic organoheteroatom compounds is undoubtedly one of the most exciting and challenging aspects in asymmetric catalysis and the application of catalytic asymmetric C–H activation reaction for the construction of chiral organoheteroatom compounds is still in its infancy. In this Review, we highlighted the main progress on the corresponding catalytic asymmetric reactions that apply to the construction of Si-, P-, and S-stereogenic centers and related chiral organoheteroatom compounds in a catalytic C–H activation fashion. [ABSTRACT FROM AUTHOR]

Simple modifications of our novel ligand (Xing-Phos) were presented in this work, and a series of aromatic tertiary amide derived non-biaryl atropisomers were successfully synthesized in good yields. In addition, it was found that the multifunctional aromatic tertiary amide derived non-biaryl atropisomers exhibited an excellent endo -selectivity in the silver-catalyzed [3+2]-cycloaddition of azomethine ylides with N -aromatic maleimide. And especially, good to high levels of enantioselectivity (up to 98% ee ) was obtained with a wide range of substrates in the presence of syn -( R , R S )- 2a (Xing-Phos). Furthermore, on the basis of the experimental data, it was demonstrated that a trace amount of water play an important role in the enhancement of enantioselectivity. [ABSTRACT FROM AUTHOR]

Abstract: A new family of C 2-axially chiral monophosphines (Ar-NNPs) from Ar-BINMOLs was developed for silver-catalyzed asymmetric vinylogous Mannich reaction of (furan-2-yloxy)trimethylsilane with aromatic aldimines. It was found that the enantioselective vinylogous Mannich-type reactions of trimethylsiloxyfuran with aldimines are catalyzed efficiently by silver(I) complexes of the Ar-BINMOL-derived chiral monophosphine. This procedure displays wide aldimine versatility, excellent yields (up to 99% isolated yields), moderate to good enantioselectivity (up to 78%ee) and exceptional diastereoselectivity (>99:1 dr) in most cases examined. The molecular structure of silver–monophosphine complex was confirmed by X-ray analysis and revealed that the benzyl group on chiral monophosphine provided dual function with weak silver–π/π–π stacking and steric repulsion to favour the diastereoselective Re-nucleophilic addition of siloxyfuran to imine. [Copyright &y& Elsevier]

Abstract: The LBAs (Lewis acid-assisted Brønsted acid catalysis) is proposed as possible mechanistic process in the simple FeCl3-catalyzed Michael reactions of chalcones with active methylene compounds in organic solvents. And iron salts were found to be effective promoters in the asymmetric Michael addition of 4-hydroxycoumarin to α,β-unsaturated ketone, which resulted in excellent yield and high level of enantioselectivity (up to 91% ee) in the presence of low catalytic amount of iron and simple chiral primary amine. [Copyright &y& Elsevier]

• Swollen-induced in-situ encapsulation of catalysts in cross-linked polysiloxane elastomers polymer. • Silicone rubber-based microchannel reactor was employed for asymmetric transforms. • Cross-linked polysiloxane elastomers was proved to be easily recycled by filtration or pick-up,reused by several times and exhibits excellent enantioselectivities 94–96% ees The immobilization of molecular catalysts to fabricate heterogeneous catalysts for catalytic asymmetric transformations is extremely important and has attracted great attentions. Herein we developed a simple and new strategy for the heterogenization of homogeneous molecular complexes into the cross-linked polymer. It is demonstrated for the first time that the cross-linked polysiloxane elastomers can be applied for the swollen-induced in-situ encapsulation of homogeneous catalysts with or without chiral ligands. The swollen-induced in-situ encapsulation of silver catalyst system in the cross-linked polysiloxane elastomers led to the formation of silicone rubber-based hierarchically porous that could be used in asymmetric [3+2] cycloaddition, asymmetric tandem conjugate addition−elimination reaction and oxidation of hydrosilanes to silanols. The swollen-induced in-situ encapsulation of chiral silver complex in the cross-linked polysiloxane elastomers was proved to be easily recycled by filtration or pick-up and reused by several times. The simplest heterogeneous catalysis by the strategy of swollen-induced in-situ encapsulation can be extended to the encapsulation of chiral metal catalysts into different polymeric materials for the heterogenization of homogeneous catalysis. [Display omitted] [ABSTRACT FROM AUTHOR]