A highly enantioselective hydrogenation of various sodium α-arylethenylsulfonates catalyzed by Rh/chiral ferrocenyl bisphosphorus ligand (Wudaphos) was successfully developed to construct a series of chiral α-arylethylsulfonic acids in the presence of CF3SO3H with full conversion and good to excellent enantioselectivity (>99% conversion, up to 96% ee) under mild reaction conditions for the first time. Moreover, the control experiment results showed that the non-covalent ion pair interaction between the α-arylethenylsulfonic acid and the Wudaphos ligand plays an important role in this asymmetric hydrogenation system.

A highly efficient asymmetric hydrogenation of azepine/oxazepine-type seven-member cyclic imine hydrochlorides was successfully developed using Rh/bisphosphine-thiourea ligand ZhaoPhos, affording various chiral seven-member cyclic amines with full conversions, high yields, and excellent enantioselectivities (up to 96% yield, >99% ee). Additionally, this asymmetric hydrogenation can proceed well on gram scale with excellent ee value. Moreover, control experimental results displayed that the anion-bonding interaction between the chloride ion of the substrate and thiourea motif of the ZhaoPhos played an important role to obtain excellent enantioselectivity.

The t-Bu-Wudaphos was successfully applied into Rh-catalyzed asymmetric hydrogenation of α,α-disubstituted terminal olefins bearing a carboxy-directed group with excellent reactivities and enantioselectivities via the ion pair noncovalent interaction (up to >99% conversion, 98% yield, 98% ee) under mild reaction conditions without base. In addition, control experiments were conducted, and the results demonstrated that the ion pair noncovalent interaction between ligand and substrate played an important role in achieving an outstanding performance in this asymmetric hydrogenation.

Asymmetric hydrogenation of α-substituted ethenylphosphonic acids has been successfully achieved by Rh/ferrocenyl chiral bisphosphorus ligand (SPO-Wudaphos) through noncovalent ion-pair interaction between the substrate and catalyst under mild reaction conditions without base. A series of chiral phosphonic acids were obtained with excellent results (up to 98% ee, >99% conversion, 2000 TON). Moreover, the control experiments showed that the noncovalent ion-pair interaction was critical in this asymmetric hydrogenation.

A series of tridentate ferrocene-based amino-phosphine acid (f-Ampha) ligands have been successfully developed. The f-Ampha ligands are extremely air stable and exhibited excellent performance in the Ir-catalyzed asymmetric hydrogenation of ketones (full conversions, up to >99% ee, and 500 000 TON). DFT calculations were performed to elucidate the reaction mechanism and the importance of the −COOH group. Control experiments also revealed that the −COOH group played a key role in this reaction.

Upon incorporation of a noncovalent ion pair interaction, a new chiral ferrocenyl bisphosphorus ligand t-Bu-Wudaphos was developed. t-Bu-Wudaphos can be easily synthesized with very high diastereoselectivity as a highly air stable solid. The new ligand exhibited excellent reactivities and enantioselectivities in the asymmetric hydrogenation of α-methylene-γ-keto-carboxylic acids via an ion pair noncovalent interaction (up to >99% conversion, >99% ee).

Cobalt-catalyzed highly (Z)-selective semihydrogenation of alkynes using molecular H2 was developed using commercially available and cheap cobalt precursors. A variety of (Z)-alkenes were obtained in moderate to excellent selectivities [(Z)-alkene/(E)-alkene/alkane ratio up to >99 : 1 : 1] and it was found that the readily available ethylenediamine ligand is crucial in determining the selectivity.

Asymmetric hydrogenation of various 3-substituted maleic anhydrides catalyzed by Rh/bisphosphine-thiourea (ZhaoPhos) under mild conditions was successfully developed. A wide range of 3-alkyl and 3-aryl maleic anhydrides were hydrogenated well to provide the desired products 3-substituted succinic anhydrides in one hour with excellent results (full conversions, up to 99% yield, 99% ee, 3000 TON). Importantly, we developed a creative and efficient synthetic route to construct the key intermediate of the hypoglycemic drug mitiglinide through our catalytic system.

New, efficient and highly stereoselective methods were developed for the synthesis/modification of Wudaphos type ligands. It was found that the “three hindered quadrant” model is crucial to ensure high enantiomeric control and that the substituents on the phosphine atom should be electron rich to increase the reactivity. Moreover, a new SPO-Wudaphos ligand was developed, which exhibited good to excellent enantioselectivities in the asymmetric hydrogenation of α-methylene-γ-keto carboxylic acids.

Tridentate f-amphox ligands were successfully applied to the iridium-catalyzed asymmetric hydrogenation of various α-amino ketones to afford a series of chiral 1,2-amino alcohols with excellent results (all products up to >99% conversion and >99% ee, TON up to 500 000). The products chiral 1,2-amino alcohols are important motifs in many pharmaceuticals, chiral auxiliaries and ligands. Our catalytic system provided an efficient synthetic route to prepare an important chiral intermediate of (S)-phenylephrine with practical industrial potential (up to 200 000 TON and >99% ee), which is the enantiomer of a famous α-adrenergic receptor agonist.

We successfully applied tridentate f-amphox ligands to the iridium-catalytic asymmetric hydrogenation of various α-hydroxy ketones to afford the corresponding chiral 1,2-diols with excellent results (almost all products up to 99% yield and >99% ee). The resulting chiral 1,2-diols and their derivatives are important synthetic and pharmaceutical intermediates. Our catalytic system displayed extremely high activity, achieving up to 1 000 000 turnover number (TON). The great performance of this asymmetric hydrogenation makes the preparation of various chiral 1,2-diols highly practical with great potential.

A series of highly modular chiral axial-unfixed biphenyl phosphine–oxazoline ligands were developed via a simple synthetic route using readily available (S)-(+)-2-phenylglycinol as a starting material. Modular oxazoline motifs can be efficiently constructed through various easily accessible carboxylic acids. These ligands were successfully applied to Ir-catalyzed asymmetric hydrogenation of α,β-unsaturated carboxylic acids to afford chiral α-substituted carboxylic acids with excellent results (up to 97% ee, 98% yield, 2000 TON).

Correction for ‘Iridium catalysts with modular axial-unfixed biphenyl phosphine–oxazoline ligands: asymmetric hydrogenation of α,β-unsaturated carboxylic acids’ by Qian Wang et al., Org. Chem. Front., 2017, DOI: 10.1039/c6qo00677a.

AbstractInspired by the unique character of enzymes, we developed novel chiral SPO (secondary-phosphine-oxide) ligand (SPO-Wudaphos) which can enter into both ion pair and H-bond noncovalent interactions. The novel chiral SPO-Wudaphos exhibited excellent results in the asymmetric hydrogenation of α-methylene-γ-keto carboxylic acids, affording the chiral γ-keto acids with up to over 99 % ee. A series of control experiments and DFT calculations were conducted to illustrate the critical roles of both the ion pair and H-bond noncovalent interactions.

AbstractInspired by the unique character of enzymes, we developed novel chiral SPO (secondary-phosphine-oxide) ligand (SPO-Wudaphos) which can enter into both ion pair and H-bond noncovalent interactions. The novel chiral SPO-Wudaphos exhibited excellent results in the asymmetric hydrogenation of α-methylene-γ-keto carboxylic acids, affording the chiral γ-keto acids with up to over 99 % ee. A series of control experiments and DFT calculations were conducted to illustrate the critical roles of both the ion pair and H-bond noncovalent interactions.

AbstractWe have successfully developed a series of novel and modular ferrorence-based amino-phosphine-alcohol (f-Amphol) ligands, and applied them to iridium-catalyzed asymmetric hydrogenation of various simple ketones to afford the corresponding chiral alcohols with excellent enantioselectivities and conversions (98–99.9 % ee, >99 % conversion, turnover number up to 200 000). Control experiments and density functional theory (DFT) calculations have shown that the hydroxyl group of our f-Amphol ligands played a key role in this asymmetric hydrogenation.

The first interrupted asymmetric hydroaminomethylation reaction was developed. The challenging trans-1,2-disubstituted olefins were employed as substrates, and a series of valuable chiral pyrrolidinones and pyrrolidines were obtained in high yields with high regioselectivities and excellent enantioselectivities. Several synthetic transformations were conducted, demonstrating the high synthetic utility of our method. A creative route for the synthesis of vernakalant and Enablex was also developed.

We have successfully developed a highly enantioselective hydrogenation of various 3-aryl and 3-methyl maleinimides to access enantiomerically pure 3-substituted succinimides catalyzed by Rh/bisphosphine-thiourea (ZhaoPhos). This efficient catalytic system furnished the desired 3-substituted succinimide products with high yields and enantioselectivities (up to 99% yield, full conversions, almost all 3-aryl succinimide products up to 99% ee, and 3-methyl succinimide with 83% ee). Our catalytic system has a strong substrate tolerance and generality. Whether the N-substituted group of maleinimides is H or other protecting groups, the maleinimides were hydrogenated well (up to >99% ee, 99% yield). Moreover, the hydrogenation succinimide products can be readily utilized for the construction of biologically active molecules, such as chiral amides and pyrrolidines.Keywords: 3-substituted succinimides; asymmetric hydrogenation; bisphosphine-thiourea; enantioselectivity; ligand

The asymmetric hydrogenation of β-amino nitroolefins has been successfully achieved by rhodium/bis(phosphine)-thiourea L1 with excellent enantioselectivities and yields (up to 96% ee, 96% yield, >99% conversion, TON up to 1000) under mild conditions. Chiral β-amino nitroalkane products and their derivatives are versatile intermediates in organic synthesis.

A readily available ruthenium(II) catalyst was developed for the catalytic hydrogenation of aldehydes with a TON (turnover number) up to 340000. It can be performed without base and solvent, showing highly industrial potential. High chemoselectivity can be achieved in the presence of alkenyl and ketone groups. Further application of this protocol in glucose reduction showed good efficiency. Theoretical studies revealed that the rate-determining step is the hydrogenation step, not the carboxylate-assisted H2 activation step.

A series of modular and rich electronic tridentate ferrocene aminophosphoxazoline ligands (f-amphox) have been successfully developed and used in iridium-catalytic asymmetric hydrogenation of simple ketones to afford corresponding enantiomerically enriched alcohols under mild conditions with superb activities and excellent enantioselectivities (up to 1 000 000 TON, almost all products up to >99% ee, full conversion). The resulting chiral alcohols and their derivatives are important intermediates in pharmaceuticals.

A tetraphosphoramidite ligand was successfully applied to a Rh-catalyzed hydroformylation of various symmetrical and unsymmetrical alkynes to afford corresponding α,β-unsaturated aldehyde products in good to excellent yields (up to 97% yield). Excellent chemo- and regioselectivities and high activities (up to 20 000 TON) were achieved. The corresponding α,β-unsaturated aldehyde products can be transformed into many useful and important organic molecules, such as indenamine derivatives and lukianol pyrroles. This great performance makes the hydroformylation of alkynes highly practical with great potential.

We have successfully developed a strategy for the first time for the enantioselective Rh-TaniaPhos catalyzed asymmetric hydrogenation of unprotected β-enamine phosphonates to free β-amino phosphonates directly with good enantioselectivities (80%–86% ee) and high conversions (>99% conversion). The resulting chiral free β-amino phosphonates and their derivatives are important intermediates in biochemistry and pharmaceuticals.

The catalytic transformation of the most abundant cellulose to valuable platform chemicals is one of the significant issues to overcome the shortage of fossil fuels. Herein, we reported the first example of Ru-based homogeneous catalyst for the highly selective conversion of cellobiose and ball-milled cellulose to hexitols (including sorbitol, mannitol, and 1,4-sorbitan) under an acidic condition with the yield of 94.5% and 56.4%, respectively. The main features of this catalytic system were the high conversion efficiency of biomass, mild reaction condition (100 °C), and low catalyst loading, which was 1/20 of the related Ru/C heterogeneous catalyst. This work opened up a new avenue for the transformation of cellulose to hexitols under mild conditions.

We successfully developed new tetraphosphite ligands L1–L5 and applied them to the rhodium-catalyzed hydroformylation of terminal and internal olefins. High catalytic reactivities and excellent regioselectivities for linear aldehydes were obtained in the rhodium-catalyzed hydroformylation of simple olefins (l/b ratio up to 90, 98.9% linear selectivity, 99.2% conversion) using the tetraphosphite ligand L2. And the tetraphosphite ligand L2 also displayed moderate to good linear regioselectivities for challenging substrates styrene and internal olefin 2-octene.

Asymmetric hydrogenation of 4-substituted cyclic enamido esters catalyzed by a rhodium–TangPhos complex provides an efficient method for the synthesis of chiral 4-substituted oxazolinones with excellent yields and good enantioselectivities. The products are valuable chiral building blocks and the applications as chiral auxiliaries and pharmaceuticals are well-known.Asymmetric hydrogenation of 4-substituted cyclic enamido esters catalyzed by a rhodium–TangPhos complex provides an efficient method for the synthesis of chiral 4-substituted oxazolinones with excellent yields and good enantioselectivities. The products are valuable chiral building blocks and applications as chiral auxiliaries and pharmaceuticals are well-known.

A hydrazine group-containing nitrogen–phosphine ligand and corresponding ruthenium complexes were synthesized. When these complexes were used for hydrogenation of esters, excellent performance was observed (TON up to 17200). A wide substrate scope was suitable for this catalytic system.

Highly enantioselective catalytic asymmetric hydrogenation of α-CF3-enamides has been achieved by employing rhodium–DuanPhos as the catalyst, which provides a readily accessible method for the synthesis of chiral trifluoromethylated amines. The reaction has a broad substrate scope; both aryl- and alkyl-substituted α-CF3-enamides worked smoothly and afford the corresponding chiral amines in high yields and excellent enantioselectivities (up to 99% ee).

A new tetradentate ruthenium complex has been developed for hydrogenation of esters. The catalyst’s structure features a pyridinemethanamino group and three tight chelating five-membered rings. The structure character is believed to be responsible for its high stability and high carbonylation-resistant properties. Thus, this catalyst shows outstanding performance in the catalytic hydrogenation of a variety of esters, especially for fatty acid esters, which may be used in practical applications. New insight on designing hydrogenation catalyst for reducing esters to alcohols has been provided through theoretical calculations.

Rh/(R,S)-JosiPhos complex-catalyzed asymmetric hydrogenation of o-alkoxy tetrasubstituted enamides has been achieved, and it furnished a set of β-amino alcohol analogues in high yields and excellent enantiomeric excesses (>99% conversion, up to 99% ee).This method provides valuable chiral building blocks in chiral pharmaceuticals and useful motifs for catalysts.

Catalyzed by [Rh(COD)Binapine]BF4, the asymmetric hydrogenation of 2-pyridine ketones has been achieved with excellent enantioselectivities (enantiomeric excesses up to 99%) under mild conditions. This method is suitable for various kinds of 2-pyridine ketones and their derivatives. A number of enantiomerically pure chiral 2-pyridine-aryl/alkyl alcohols were prepared through hydrogenation, which can be used directly in organic synthesis.

By employing a rhodium–Duanphos complex as the catalyst, β-alkyl (Z)-N-acetyldehydroamino esters were smoothly hydrogenated in a highly efficient and enantioselective way. Excellent enantioselectivities together with excellent yields were achieved for a series of substrates. An efficient approach for the synthesis of the intermediate of the orally administered anti-diabetic drugs Alogliptin and Linagliptin in the DPP-4 inhibitor class was also developed.

Asymmetric hydrogenation of tetrasubtitued α-acetoxy β-enamido esters with rhodium catalysts based on chiral diphosphine ligands provides an efficient and concise route to the synthesis of chiral α-hydroxyl-β-amino acid derivatives in excellent enantioselectivities. The products are valuable chiral building blocks in many biologically active compounds and have important applications in organic synthesis.

The efficient and highly enantioselective catalytic asymmetric hydrogenation of β-acetylamino acrylosulfone has been achieved by employing Rhodium-TangPhos as catalyst. A series of β-amido sulfone products are obtained with excellent yields and good enantioselectivities.Keywords: asymmetric hydrogenation; diphosphine ligand; enantioselectivity; rhodium; β-amido sulfones

Highly regioselective and enantioselective asymmetric hydrogenation of cyclic dienamides catalyzed by an Rh-DuanPhos complex has been developed, which provides a readily accessible method for the synthesis of chiral cyclic allylic amines in excellent enantioselectivities (up to 99% ee). The products are valuable chiral building blocks and could be easily transformed to multisubstituted cyclohexane derivatives.

An efficient and highly enantioselective catalytic asymmetric hydrogenation of β-acylamino nitroolefins has been realized by using Rh-TangPhos as the catalyst. A series of β-amino nitroalkane products, which are versatile intermediates in organic synthesis, were obtained with high yield and good enantioselectivity.

A novel method to desymmetrize meso-anhydrides into lactones via asymmetric hydrogenation catalyzed by the Ir–C3*-TunePhos complex has been developed. Various chiral lactones were synthesized with full conversion and excellent enantioselectivity under high reaction temperature.

Asymmetric hydrogenation of various 3-substituted maleic anhydrides catalyzed by Rh/bisphosphine-thiourea (ZhaoPhos) under mild conditions was successfully developed. A wide range of 3-alkyl and 3-aryl maleic anhydrides were hydrogenated well to provide the desired products 3-substituted succinic anhydrides in one hour with excellent results (full conversions, up to 99% yield, 99% ee, 3000 TON). Importantly, we developed a creative and efficient synthetic route to construct the key intermediate of the hypoglycemic drug mitiglinide through our catalytic system.

Cobalt-catalyzed highly (Z)-selective semihydrogenation of alkynes using molecular H2 was developed using commercially available and cheap cobalt precursors. A variety of (Z)-alkenes were obtained in moderate to excellent selectivities [(Z)-alkene/(E)-alkene/alkane ratio up to >99:1:1] and it was found that the readily available ethylenediamine ligand is crucial in determining the selectivity.

We successfully applied tridentate f-amphox ligands to the iridium-catalytic asymmetric hydrogenation of various α-hydroxy ketones to afford the corresponding chiral 1,2-diols with excellent results (almost all products up to 99% yield and >99% ee). The resulting chiral 1,2-diols and their derivatives are important synthetic and pharmaceutical intermediates. Our catalytic system displayed extremely high activity, achieving up to 1000000 turnover number (TON). The great performance of this asymmetric hydrogenation makes the preparation of various chiral 1,2-diols highly practical with great potential.

A series of highly modular chiral axial-unfixed biphenyl phosphine–oxazoline ligands were developed via a simple synthetic route using readily available (S)-(+)-2-phenylglycinol as a starting material. Modular oxazoline motifs can be efficiently constructed through various easily accessible carboxylic acids. These ligands were successfully applied to Ir-catalyzed asymmetric hydrogenation of α,β-unsaturated carboxylic acids to afford chiral α-substituted carboxylic acids with excellent results (up to 97% ee, 98% yield, 2000 TON).

Correction for ‘Iridium catalysts with modular axial-unfixed biphenyl phosphine–oxazoline ligands: asymmetric hydrogenation of α,β-unsaturated carboxylic acids’ by Qian Wang et al., Org. Chem. Front., 2017, DOI: 10.1039/c6qo00677a.

Tridentate f-amphox ligands were successfully applied to the iridium-catalyzed asymmetric hydrogenation of various α-amino ketones to afford a series of chiral 1,2-amino alcohols with excellent results (all products up to >99% conversion and >99% ee, TON up to 500000). The products chiral 1,2-amino alcohols are important motifs in many pharmaceuticals, chiral auxiliaries and ligands. Our catalytic system provided an efficient synthetic route to prepare an important chiral intermediate of (S)-phenylephrine with practical industrial potential (up to 200000 TON and >99% ee), which is the enantiomer of a famous α-adrenergic receptor agonist.

A hydrazine group-containing nitrogen–phosphine ligand and corresponding ruthenium complexes were synthesized. When these complexes were used for hydrogenation of esters, excellent performance was observed (TON up to 17200). A wide substrate scope was suitable for this catalytic system.

By employing a rhodium–Duanphos complex as the catalyst, β-alkyl (Z)-N-acetyldehydroamino esters were smoothly hydrogenated in a highly efficient and enantioselective way. Excellent enantioselectivities together with excellent yields were achieved for a series of substrates. An efficient approach for the synthesis of the intermediate of the orally administered anti-diabetic drugs Alogliptin and Linagliptin in the DPP-4 inhibitor class was also developed.

We have successfully developed a strategy for the first time for the enantioselective Rh-TaniaPhos catalyzed asymmetric hydrogenation of unprotected β-enamine phosphonates to free β-amino phosphonates directly with good enantioselectivities (80%–86% ee) and high conversions (>99% conversion). The resulting chiral free β-amino phosphonates and their derivatives are important intermediates in biochemistry and pharmaceuticals.