Technical articles
Chiral Catalyst and Ligand Selection Guide: From Reaction Task to Catalytic System Screening
Chiral Catalyst and Ligand Selection Guide: From Reaction Task to Catalytic System Screening
1. What Are Chiral Catalysts and Chiral Ligands?
The goal of chiral catalysis is to preferentially generate one enantiomer during a reaction. In modern organic synthesis, two common approaches are the metal–chiral ligand system and the small-molecule organocatalytic system. The 2001 Nobel Prize in Chemistry was awarded for asymmetric hydrogenation and asymmetric oxidation in catalytic asymmetric synthesis, while the 2021 Nobel Prize in Chemistry was awarded for asymmetric organocatalysis. These two awards correspond closely to two of the most widely used types of methods in today’s laboratories.
Object | Meaning | Role in the Reaction | Common Forms |
Chiral catalyst | A catalytic system or catalytic molecule that enables preferential formation of one enantiomer | Determines reaction activity and enantioselectivity | Metal complex catalysts; small-molecule organocatalysts |
Chiral ligand | A molecule that coordinates to a metal and creates a chiral environment | Adjusts the spatial structure and electronic environment around the metal center | Chiral diphosphine ligands, phosphinooxazoline ligands, bisoxazoline ligands, salen ligands |
Small-molecule organocatalyst | A chiral catalyst in its own right, without relying on a metal ligand | Achieves stereocontrol through enamine, iminium ion, hydrogen-bonding, ion-pairing, and related activation modes | Proline catalysts, imidazolidinone catalysts, chiral phosphoric acids, isothiourea catalysts |
If the reaction must rely on a metal center for coordination, insertion, migration, or a redox cycle, chiral ligands should be considered first. If the substrate can be activated through enamine formation, iminium ion formation, hydrogen bonding, or Brønsted acid activation, organocatalysis should be considered first.
2. Define the Reaction Task First, Then Determine the Direction for Selecting a Chiral Catalytic System
When selecting chiral catalysts and ligands experimentally, the first step is to identify the type of asymmetric transformation involved. Different reaction tasks correspond to different catalytic modes, commonly used ligand types, and priorities in condition screening.
2.1 Asymmetric Hydrogenation and Reduction
If the target is the asymmetric reduction of alkenes, imines, or carbonyl compounds, the first distinction should be whether the reaction is asymmetric hydrogenation involving hydrogen gas or asymmetric transfer hydrogenation involving a hydrogen donor. Asymmetric hydrogenation of alkenes and some imines often starts from rhodium, iridium, or ruthenium systems with chiral phosphine ligands. Asymmetric transfer hydrogenation of ketones and imines often starts from ruthenium–arene–chiral diamine systems. For hydrogen-gas-based asymmetric hydrogenation of carbonyl substrates such as aryl alkyl ketones, ruthenium–diphosphine–diamine systems are commonly used. In experimental selection, substrate type, hydrogen source, metal precatalyst, and the ligand or preassembled complex should be evaluated together for compatibility.
2.2 Asymmetric Allylic Substitution and Related Palladium-Catalyzed Reactions
If the target reaction is allylic substitution, allylic alkylation, or a related palladium-catalyzed asymmetric transformation, phosphinooxazoline ligands, known as PHOX ligands, can be considered first as a class of P,N ligands. PHOX ligands are widely used in these reactions, and their phosphine group, oxazoline ring, and backbone structure can be systematically screened. In experiments, the comparison should not focus only on the ligand itself. The metal center, P,N coordination combination, and leaving group of the substrate should also be examined, because these factors together influence the formation mode of the allylpalladium intermediate, as well as the final regioselectivity and enantioselectivity.
2.3 Asymmetric Epoxidation
For asymmetric epoxidation, the substrate type should be clarified first.
Reaction Task | System to Consider First | Substrate Suitability |
Asymmetric epoxidation of allylic alcohols | Tartrate–titanium system | The substrate contains an allylic alcohol structure |
Asymmetric epoxidation of unfunctionalized alkenes | Manganese–salen system | The substrate does not rely on allylic alcohol directing |
The classic substrate class for Sharpless asymmetric epoxidation is allylic alcohols. Jacobsen–Katsuki asymmetric epoxidation is mainly directed toward unfunctionalized alkenes. Both belong to asymmetric epoxidation, but their substrate requirements, active species, and experimental entry points are different.
2.4 Lewis Acid-Activated Asymmetric Reactions
If the reaction relies on a metal center to coordinate and activate the substrate, such as cyclopropanation, certain cycloadditions, or some Lewis acid-promoted asymmetric reactions, bisoxazoline ligands, or BOX ligands, can be considered first. BOX ligands can coordinate with many metals and are especially widely used in complexes with copper. In such systems, ligand substituents, metal type, and anions can all significantly influence selectivity.
2.5 Organocatalytic Carbonyl Transformations
If the substrate is more suitable for activation through enamine formation, iminium ion formation, hydrogen bonding, or Brønsted acid activation, organocatalysis should be considered first. Proline-catalyzed direct asymmetric aldol reactions represent the enamine activation pathway. MacMillan imidazolidinone systems represent the iminium ion activation pathway. Chiral phosphoric acids represent Brønsted acid-type stereochemical induction. When metal residues need to be avoided, or when the substrate itself is more suitable for facial selectivity control by a small-molecule catalyst, these systems are often worth screening first.
2.6 Kinetic Resolution and Asymmetric Acyl Transfer
If the substrate is already racemic and the goal is to obtain one enantiomer through selective acylation, esterification, or a related step, the reaction should be evaluated as a kinetic resolution. Isothiourea catalysts such as HBTM, or homobenzotetramisole, are typical tools in this route and are commonly used for kinetic resolution of secondary alcohols and asymmetric acyl transfer.
3. Judge by Catalytic Mode: How to Choose Between Metal–Chiral Ligand Systems and Organocatalytic Systems
3.1 When to Prioritize Metal–Chiral Ligand Systems
In the following situations, it is appropriate to start with a metal–chiral ligand system:
Question to Ask | When to Prioritize a Metal–Chiral Ligand System |
How is the substrate activated? | Metal coordination, insertion, migration, or a redox cycle is required |
Where does the stereoselectivity mainly come from? | From the three-dimensional coordination environment around the metal center |
Does the reaction rely on a rigid chiral space? | A bidentate or multidentate ligand is needed to establish a fixed spatial arrangement |
What are the requirements for reaction performance? | Both relatively high activity and high enantioselectivity are required |
Most mature asymmetric catalysts are still based on the combination of a metal and a chiral organic ligand. Chiral ligands modify the reactivity and selectivity of the metal center, allowing the reaction to preferentially form one enantiomer. At the same time, many highly efficient systems developed later are not limited to C2-symmetric ligands; unsymmetrical P,N ligands can also be highly effective.
3.2 When to Prioritize Organocatalytic Systems
In the following situations, it is appropriate to start with organocatalysis:
Question to Ask | When to Prioritize an Organocatalytic System |
How is the substrate activated? | It can be activated through enamine formation, iminium ion formation, hydrogen bonding, or ion pairing |
Must metal residues be avoided? | Yes |
Are the conditions suitable for a small-molecule catalyst? | Yes |
Source of selectivity | Covalent intermediates or multiple noncovalent interactions between the catalyst and the substrate |
4. Main Sources of Stereoselectivity in Chiral Catalysis
4.1 Spatial Structure Around the Metal Center
This is the most common source of stereocontrol in metal–ligand systems. The ligand determines which directions around the metal are more accessible to the substrate and which directions are blocked by steric repulsion, thereby influencing coordination, insertion, migration, and elimination processes. Diphosphine ligands, PHOX ligands, and BOX ligands all follow this general logic.
4.2 Multipoint Recognition Between the Catalyst and the Substrate
In chiral phosphoric acid catalysis and hydrogen-bonding catalysis, stereoselectivity often comes from hydrogen bonding, ion pairing, and spatial enclosure between the catalyst and the substrate. These systems do not rely on a metal coordination sphere. Instead, they depend on the direction and binding mode by which the substrate approaches the catalyst.
4.3 Configurational Control Through Covalent Intermediates
Catalysts such as proline and imidazolidinones often first form enamine or iminium ion intermediates with the substrate, and facial selectivity is controlled at this stage. In such cases, the catalyst backbone, acid additives, solvent, and temperature need to be optimized.
4.4 Overall Composition of the Active Species
In some systems, the stereochemical outcome is not determined only by the ligand itself. It is also related to the metal salt, anion, oxidant, acid or base additive, and other components. The sensitivity of BOX systems to anion changes is a typical example. During experimental optimization, if only the ligand is changed while these factors are not examined, the conclusions may be misleading.
5. Experimental Selection Steps for Chiral Catalysts and Ligands
5.1 Step 1: Determine Whether Conditions Are Being Screened from Scratch or Adjusted Based on Existing Literature
Situation | Appropriate Approach |
Screening conditions from scratch | First cover different catalytic modes or different ligand families, then refine the screening |
Existing literature is relatively close | First retain the original catalytic mode, then adjust the metal source, ligand, and additives according to substrate differences |
If the substrate skeleton, functional group distribution, and reaction type are close to those reported in the literature, local adjustment based on the existing system can be prioritized. If the reaction task itself is different, the required catalytic mode and ligand type should be reassessed first. It is not advisable to directly start screening by simply adopting a ligand from the literature.
5.2 Step 2: Do Not Change Too Many Variables in the First-Round Screening
The goal of the first-round screening is to determine which type of system is worth continuing, not to identify the fully optimized conditions in one step.
System Type | Focus of First-Round Screening |
Metal–chiral ligand system | First fix the metal source, then compare 4 to 8 ligand families or representative ligands with clear structural differences |
Organocatalytic system | First fix the activation mode, then compare representative catalysts |
Asymmetric epoxidation | First confirm which substrate class is involved, then select the corresponding system |
Kinetic resolution | First confirm whether the substrate has a distinguishable reaction rate difference between enantiomers |
PHOX, BOX, salen, chiral diphosphines, chiral phosphoric acids, proline, imidazolidinones, and HBTM represent different types of chiral ligands, catalyst frameworks, or catalytic systems. They are not a set of choices that can be directly substituted for one another in the same reaction. Instead, they correspond to different reaction tasks, substrate activation modes, and catalytic modes.
5.3 Step 3: Do Not Judge First-Round Results by Enantiomeric Excess Alone
Enantiomeric excess, or ee, is important, but it cannot be used as the sole criterion. In first-round screening, conversion, isolated yield, enantiomeric excess, regioselectivity, and diastereoselectivity should all be recorded. For kinetic resolution experiments, substrate ee, product ee, conversion, and the selectivity factor should also be recorded. The efficiency of a kinetic resolution cannot be judged only by the product ee at a single time point. Some systems may give high ee but have low conversion, narrow conditions, or high sensitivity to substrate variation, making them not necessarily suitable for further method development.
6. Interpreting First-Round Screening Results and Deciding the Next Adjustment Direction
The key purpose of first-round screening is to determine whether the route has a promising direction and what should be adjusted first in the next step.
6.1 Low Conversion but Some Enantioselectivity: Improve Activity First
This suggests that the current chiral environment may be reasonable, while the main issue is insufficient reaction progress. In this case, it is usually better to first adjust the metal source, catalyst loading, temperature, concentration, and reaction time. There is no need to immediately replace the entire ligand or catalyst family.
6.2 High Conversion but Low Enantioselectivity: Change the Chiral Environment First
This suggests that the reaction itself can proceed, but the current catalytic system does not sufficiently distinguish between the two enantiotopic faces. In this case, the ligand family, catalyst framework, or catalytic mode should be adjusted first, rather than repeatedly making minor changes to reaction time and temperature.
6.3 Both Conversion and Enantioselectivity Are Low: Recheck the Catalytic Mode First
This type of result often indicates that the issue is not merely a matter of condition details. The reaction task or catalytic mode itself may have been chosen incorrectly. In this case, it is necessary to reassess whether the substrate is more suitable for a metal–chiral ligand system or an organocatalytic system. It is not advisable to continue making fragmented adjustments based on the original conditions.
6.4 The Result Looks Good but Reproducibility Is Poor: Check Operational Conditions First
If the first result is good but repeated experiments fluctuate significantly, the first things to check are whether the catalyst needs to be preassembled, whether the order of addition is consistent, and whether the solvent and temperature are stable. Only after these issues are clarified should substrate expansion or reaction scale-up be considered.
6.5 A Practical Decision Sequence
The interpretation of first-round screening results can be condensed into the following four points:
1. If there is selectivity but insufficient activity, improve activity first.
2. If there is activity but insufficient selectivity, change the chiral environment first.
3. If both activity and selectivity are poor, check the catalytic mode first.
4. If the result is unstable, troubleshoot the operational conditions first.
7. Navigation Table for Representative Chemicals Related to Chiral Catalysts and Ligands：Select Tables 1–5 by Research or Experimental Objective
Research or Experimental Objective | Recommended Table | Why Start with This Table | Suggested Related Table | Navigation Notes |
Conducting aldol reactions, Mannich reactions, Michael additions, imine-activation reactions, or comparing organocatalytic routes such as proline, imidazolidinone, and chiral phosphoric acid catalysis | Table 1 | Table 1 focuses on small-molecule organocatalysts, chiral phosphoric acids, and BINOL frameworks. It is suitable for first determining whether the reaction belongs to enamine catalysis, iminium ion catalysis, Brønsted acid catalysis, or acyl-transfer catalysis. | Table 5 | If preliminary results show that metal participation is needed for activation, or if organocatalysis and metal catalysis need to be compared in parallel, Table 5 can be consulted for metal precatalysts and preassembled complexes. |
Conducting asymmetric hydrogenation, asymmetric transfer hydrogenation, or screening chiral phosphine ligands such as BINAP, DuPhos, DIPAMP, and Josiphos | Table 2 | Table 2 focuses on chiral diphosphine ligands and chiral diamine ligands. It is suitable for first judging whether the reaction should proceed through a rhodium, iridium, or ruthenium route based on ligand framework and metal coordination mode. | Table 5 | After the ligand is selected, the specific metal source or preassembled ruthenium catalyst usually needs to be considered together. Table 5 can supplement the metal component. |
Conducting palladium-catalyzed asymmetric allylic substitution, allylic alkylation, amination, etherification, or comparing coordination-type chiral ligands such as PHOX, Trost ligands, BOX, and PYBOX | Table 3 | Table 3 groups P,N ligands, oxazoline ligands, and Trost ligands together, making it easier to distinguish whether the reaction should follow a palladium-catalyzed allylic substitution route or a copper- and other metal-mediated coordination-activation route. | Tables 5 and 2 | If the reaction clearly requires support from palladium, copper, iridium, or other metal sources, Table 5 can be consulted. If diphosphine systems are later included for comparison, Table 2 may also be reviewed. |
Conducting asymmetric epoxidation of allylic alcohols or asymmetric epoxidation of unfunctionalized alkenes, and distinguishing between tartrate–titanium systems and Jacobsen manganese systems | Table 4 | Table 4 corresponds to two classic asymmetric epoxidation routes. It helps determine, based on substrate type, whether to examine the Sharpless system or Jacobsen-type salen manganese catalysts first. | Table 1 | If the project later extends to chiral phosphoric acids, BINOL frameworks, or other non-metal chiral catalytic systems, Table 1 can be consulted as well. |
Conducting copper-catalyzed Lewis acid-type asymmetric reactions, such as cyclopropanation, cycloaddition, and some nucleophilic additions, and screening nitrogen-containing ligands such as BOX and PYBOX | Table 3 | Table 3 first provides ligand families, making it easier to judge whether the substrate is better suited to stereocontrol by bisoxazoline ligands or tridentate nitrogen-containing ligands. | Table 5 | These reactions usually also require evaluation together with copper salts and other metal sources. The copper source in Table 5 can be used to build coordination-catalytic systems. |
Conducting asymmetric transfer hydrogenation of carbonyl substrates such as ketones and imines, or directly using ready-made ruthenium catalysts such as RuCl(p-cymene)[Ts-DPEN] and RuCl2[(xylbinap)][daipen] | Table 5 | Table 5 focuses on metal precatalysts and preassembled chiral metal complexes. It is suitable for experiments where the ruthenium-catalyzed route has already been identified and the researcher wants to start directly from available catalysts. | Table 2 | If it is necessary to return to the ligand level and compare diphosphine or diamine frameworks again, Table 2 can be consulted. |
Conducting kinetic resolution, asymmetric acyl transfer, or comparing HBTM-type isothiourea catalysts with other organocatalytic pathways | Table 1 | In Table 1, isothiourea catalysts are placed together with chiral phosphoric acids, proline, and imidazolidinones, making it easier to first distinguish whether the experimental goal is kinetic resolution or direct construction of asymmetric configuration. | Tables 3 and 5 | If screening results show that organocatalysis alone does not provide sufficient activity, or if the project extends to metal coordination activation systems, Tables 3 and 5 can be reviewed. |
Starting a new project where only chiral catalytic screening has been defined, but it is not yet clear whether the project should proceed through metal catalysis or organocatalysis | Tables 1 and 2 | Tables 1 and 2 correspond respectively to small-molecule organocatalysis and classic chiral ligand routes, making them suitable as two core starting points for comparison. | Tables 3, 5, and 4 | If the target gradually narrows to allylic substitution, epoxidation, or ruthenium-catalyzed hydrogenation, the corresponding Table 3, Table 4, or Table 5 can then be consulted. |
Table 1｜Small-Molecule Organocatalysts, Chiral Phosphoric Acids, and BINOL Frameworks
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Proline-type organocatalyst | 147-85-3 | L-Proline | UltraBio™, ≥99.5% | A classic proline-type organocatalyst, useful for condition screening in direct asymmetric aldol reactions, Mannich reactions, and Michael additions. | |
Chiral phosphoric acid catalyst | 929097-92-7 | (S)-3,3′-Bis(triphenylsilyl)-1,1′-binaphthyl-2,2′-diyl hydrogenphosphate | ≥99%, ≥98% ee | A chiral phosphoric acid-type Brønsted acid catalyst, useful for screening imine activation, ion-pair control, and asymmetric cyclization reactions. | |
BINOL-framework chiral source | 18531-94-7 | (R)-(+)-1,1′-Bi(2-naphthol) | ≥99% | A BINOL-framework chiral source, useful as a synthetic precursor for chiral phosphoric acids, BINOL-derived diphosphine ligands, and related chiral ligands. | |
BINOL-framework chiral source | 18531-99-2 | (S)-BINOL | ≥99% | A BINOL-framework chiral source, useful as a synthetic precursor for chiral phosphoric acids, BINOL-derived diphosphine ligands, and related chiral ligands. | |
Chiral phosphoric acid catalyst | 791616-55-2 | (R)-(-)-3,3''-Bis(triphenylsilyl)-1,1''-binaphthyl-2,2''-diyl hydrogen phosphate | ≥98% | A chiral phosphoric acid-type Brønsted acid catalyst, useful for screening imine activation, ion-pair control, and asymmetric cyclization reactions. | |
Chiral phosphoric acid catalyst | 791616-63-2 | (R)-3,3′-Bis(2,4,6-triisopropylphenyl)-1,1′-binaphthyl-2,2′-diyl hydrogenphosphate | ≥98% | A chiral phosphoric acid-type Brønsted acid catalyst, useful for screening electrophilic activation, ion-pair induction, and asymmetric addition reactions. | |
Imidazolidinone-type organocatalyst | 346440-54-8 | (2S,5S)-(-)-2-tert-Butyl-3-methyl-5-benzyl-4-imidazolidinone | ≥97% (GC) | An imidazolidinone-type organocatalyst, useful for iminium ion-activated asymmetric Diels–Alder reactions, Michael additions, and α-functionalization. | |
Chiral phosphoric acid catalyst | 874948-63-7 | (S)-3,3′-Bis(2,4,6-triisopropylphenyl)-1,1′-binaphthyl-2,2′-diyl hydrogenphosphate | ≥98% | A chiral phosphoric acid-type Brønsted acid catalyst, useful for screening electrophilic activation, ion-pair induction, and asymmetric addition reactions. | |
Isothiourea-type organocatalyst | 1316861-19-4 | (2R)-2-Phenyl-3,4-dihydro-2H-pyrimido[2,1-b][1,3]benzothiazole | ≥95% | An isothiourea-type organocatalyst, useful for kinetic resolution of secondary alcohols, asymmetric acyl transfer, and esterification selectivity screening. | |
Isothiourea-type organocatalyst | 1015248-96-0 | (2S)-2-Phenyl-3,4-dihydro-2H-pyrimido[2,1-b][1,3]benzothiazole | ≥95% | An isothiourea-type organocatalyst, useful for kinetic resolution of secondary alcohols, asymmetric acyl transfer, and esterification selectivity screening. |
Table 2｜Chiral Diphosphine Ligands and Chiral Diamine Ligands
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
SEGPHOS-type axially chiral diphosphine ligand | 244261-66-3 | (R)-(+)-5,5'-Bis(diphenylphosphino)-4,4'-bi-1,3-benzodioxole | ≥99% (HPLC) | A SEGPHOS-type axially chiral diphosphine ligand, capable of forming asymmetric hydrogenation catalytic systems with rhodium, iridium, ruthenium, and other metals; also useful for screening asymmetric addition and isomerization reactions. | |
Chiral diamine ligand | 35132-20-8 | (1R,2R)-(+)-1,2-Diphenylethylenediamine | ≥99% | A chiral diamine ligand that can form bifunctional hydrogen-transfer systems with ruthenium, used for asymmetric transfer hydrogenation of ketones, imines, and related substrates. | |
P-chiral diphosphine ligand | 136705-65-2 | (+)-1,2-Bis[(2R,5R)-2,5-diisopropylphospholano]benzene | ≥98% | A P-chiral diphosphine ligand, useful for rhodium- or iridium-catalyzed asymmetric hydrogenation, commonly applied in the selective construction of alkenes and dehydroamino acid derivatives. | |
BINOL-derived diphosphine ligand | 76189-55-4 | (R)-(+)-2,2′-Bis(diphenylphosphino)-1,1′-binaphthalene | ≥98% | A classic BINOL-derived diphosphine ligand, useful in rhodium, ruthenium, and palladium systems for asymmetric hydrogenation, allylic substitution, and coupling reactions. | |
BINOL-derived diphosphine ligand | 76189-56-5 | (S)-(-)-BINAP | ≥98% | A classic BINOL-derived diphosphine ligand, useful in rhodium, ruthenium, and palladium systems for asymmetric hydrogenation, allylic substitution, and coupling reactions. | |
P-chiral diphosphine ligand | 147253-67-6 | (-)-1,2-Bis((2R,5R)-2,5-dimethylphospholano)benzene | ≥97% | A P-chiral diphosphine ligand, useful for rhodium- or iridium-catalyzed asymmetric hydrogenation and for screening certain alkene addition and reduction reactions. | |
P-chiral diphosphine ligand | 55739-58-7 | (R,R)-DIPAMP | ≥97% | A classic P-chiral diphosphine ligand, commonly used in rhodium-catalyzed asymmetric hydrogenation and suitable for configurational construction of dehydroamino acid esters and related substrates. | |
Ferrocene-framework diphosphine ligand | 155806-35-2 | (R)-1-[(SP)-2-(Diphenylphosphino)ferrocenyl]ethyldicyclohexylphosphine | ≥97% | A ferrocene-framework mixed diphosphine ligand, useful for screening asymmetric hydrogenation, allylic substitution, and selected addition reactions. |
Table 3｜P,N Ligands, Oxazoline Ligands, and Trost Ligands
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
PYBOX tridentate ligand | 128249-70-7 | 2,6-Bis[(4R)-4-phenyl-2-oxazolinyl]pyridine | ≥98% | A tridentate nitrogen-containing chiral ligand, capable of forming Lewis acid catalytic systems with copper and other metals; useful for asymmetric addition, cyclization, and cyclopropanation. | |
PHOX ligand | 1152313-76-2 | (4S)-2-[2-(diphenylphosphino)phenyl]-4,5-dihydro-5,5-dimethyl-4-(1-methylethyl)-oxazole | ≥97% | A phosphinooxazoline ligand, useful for palladium-catalyzed asymmetric allylic substitution, Heck reactions, and related carbon–carbon bond formation. | |
Trost ligand | 138517-61-0 | (R,R)-DACH-phenyl Trost ligand | ≥95% | A diphosphine amide-type ligand, commonly used in palladium-catalyzed asymmetric allylic alkylation, amination, and etherification. | |
BOX bisoxazoline ligand | 131833-92-6 | (S,S)-2,2'-Isopropylidenebis(4-isopropyl-2-oxazoline) | ≥95% | A bisoxazoline ligand, capable of forming coordination-activation systems with copper and other metals; useful for cyclopropanation, cycloaddition, and electrophilic addition. | |
Trost ligand | 169689-05-8 | (S,S)-DACH-phenyl Trost ligand | ≥95% | A diphosphine amide-type ligand, commonly used in palladium-catalyzed asymmetric allylic alkylation, amination, and etherification. |
Table 4｜Chemicals Related to Sharpless and Jacobsen Asymmetric Epoxidation
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Titanium source for Sharpless epoxidation | 546-68-9 | Titanium(IV) isopropoxide | ≥99.9% metals basis | A key titanium source for Sharpless asymmetric epoxidation, used together with tartrate esters to construct an allylic alcohol epoxidation system. | |
Tartrate ester for Sharpless epoxidation | 13811-71-7 | Diethyl D-(-)-Tartrate | ≥99% | A chiral tartrate ester component for Sharpless asymmetric epoxidation, used to control the configuration of allylic alcohol epoxidation products. | |
Tartrate ester for Sharpless epoxidation | 87-91-2 | (+)-Diethyl L-tartrate | ≥99% | A chiral tartrate ester component for Sharpless asymmetric epoxidation, used to control the configuration of allylic alcohol epoxidation products. | |
Jacobsen-type epoxidation catalyst | 138124-32-0 | (R,R)-(-)-N,N'-Bis(3,5-di-tertbutylsalicylidene)-1,2- cyclohexanediaminomanganese(III) chloride | ≥98% | A salen manganese catalyst, useful for condition screening in asymmetric epoxidation of unfunctionalized alkenes and suitable for comparing the effects of substrate structure, oxidant, and catalyst configuration on enantioselectivity. | |
Jacobsen-type epoxidation catalyst | 135620-04-1 | (S,S)-[N,N'-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine]manganese(III) chloride | ≥98% | A salen manganese catalyst, useful for condition screening in asymmetric epoxidation of unfunctionalized alkenes and suitable for comparing the effects of substrate structure, oxidant, and catalyst configuration on enantioselectivity. | |
Jacobsen-type salen ligand precursor | 135616-36-3 | (S,S)-(+)-N,N′-Bis(3,5-di-tert-butylsalicylidene) -1,2-cyclohexanediamine | ≥98% | A salen-type chiral ligand precursor, useful for preparing manganese and other metal complexes and assembling epoxidation catalysts. |
Table 5｜Metal Precatalysts, Metal Sources, and Preassembled Chiral Metal Complexes
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Rhodium precatalyst | 35138-22-8 | Bis(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate | Rh 24.8% | A cationic rhodium precatalyst, capable of forming asymmetric hydrogenation and conjugate addition systems with chiral diphosphine ligands. | |
Palladium(0) precatalyst | 51364-51-3 | Tris(dibenzylideneacetone)dipalladium(0) | ≥99.95% metals basis | A palladium(0) precatalyst, used with PHOX, Trost, BINAP, and related ligands for asymmetric allylic substitution. | |
Ruthenium–diamine precatalyst | 192139-92-7 | RuCl(p-cymene)[(R,R)-Ts-DPEN] | ≥99.95% metals basis | A ruthenium–arene–sulfonylated diamine precatalyst, useful for asymmetric transfer hydrogenation of ketones and imines. | |
Copper Lewis acid metal source | 34946-82-2 | Copper trifluoromethanesulfonate | ≥98% | A Lewis acid-type copper source, capable of forming asymmetric coordination-catalytic systems with BOX, PYBOX, and related ligands. | |
Iridium precatalyst | 12112-67-3 | Chloro(1,5-cyclooctadiene)iridium(I) dimer | ≥97% | An iridium precatalyst, used with chiral phosphine ligands for asymmetric hydrogenation and allylic substitution. | |
Ruthenium–diamine precatalyst | 192139-90-5 | RuCl(p-cymene)[(S,S)-Ts-DPEN] | ≥97% | A ruthenium–arene–sulfonylated diamine precatalyst, useful for asymmetric transfer hydrogenation of ketones and imines. | |
Preassembled ruthenium–diphosphine–diamine catalyst | 220114-01-2 | RuCl2[(S)-xylbinap][(S)-daipen] | ≥95% | A preassembled ruthenium–diphosphine–diamine catalyst, useful for hydrogen-gas-based asymmetric hydrogenation of carbonyl substrates such as aryl alkyl ketones. | |
Preassembled ruthenium–diphosphine–diamine catalyst | 220114-32-9 | Dichloro{(R)-(+)-2,2''-bis[di(3,5-xylyl)phosphino]-1,1''-binaphthyl}[(2R)-(-)-1,1-bis(4-methoxyphenyl)-3-methyl-1,2-butanediamine]ruthenium(II) RuCl2[(R)-xylbinap][(R)-daipen] | ≥95% | A preassembled ruthenium–diphosphine–diamine catalyst, useful for hydrogen-gas-based asymmetric hydrogenation of carbonyl substrates such as aryl alkyl ketones. |
Note: The products above are representative Aladdin products. For more product specifications, search by product name, CAS number, or catalog number on the Aladdin official website.
References
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[2] Press release: The Nobel Prize in Chemistry 2021. NobelPrize.org.
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