Technical articles
Reaction Selection in Small-Molecule Synthesis: From Transformation-Type Assessment to Experimental Route Screening
Reaction Selection in Small-Molecule Synthesis: From Transformation-Type Assessment to Experimental Route Screening
In small-molecule synthesis, the first question to answer is not “What reactions are available?” but rather “What type of transformation does this step belong to?” Only after the transformation type has been clearly identified can methods be screened against substrate features, target structure, and experimental constraints so that the route remains concise.
1. First determine which category the current transformation belongs to
Common synthetic problems can first be grouped into three categories. The purpose of the table below is to establish the starting point for route assessment.
Transformation Type | Core Question | Common Tasks |
Functional group interconversion | Is the existing molecular framework basically usable, requiring only a change in functional group type or oxidation state? | Interconversion among alcohols, aldehydes, ketones, acids, esters, amines, halides, nitriles, epoxides, and related groups |
Bond construction | Does the target molecule lack a key connection, such that a new carbon-carbon bond or carbon-heteroatom bond must be formed? | Addition, substitution, condensation, cross-coupling, acylation, amination |
Skeletal modification | Is it necessary to change the ring system, chain length, or connectivity, rather than simply changing a functional group? | Cyclization, ring opening, rearrangement, homologation, skeletal reorganization |
2. Substrate constraints and target structure jointly define the method space
Even for the same target transformation, the preferred method often changes when applied to different substrates. Route assessment cannot rely only on “which reactions are theoretically possible.” It must also begin with what the substrate can tolerate and what the target structure requires.
(1) First identify which sites must be preserved
Existing stereocenters, positions prone to racemization, acidic hydrogens, substituents liable to migrate, and aromatic or heteroaromatic rings that may undergo competing reactions can all directly affect route selection. When a substrate contains many structural elements that must remain unchanged, method screening should first assess whether those sites will be affected, and only then consider whether there is literature precedent for the reaction.
(2) Next identify which functional groups are sensitive to the reaction conditions
Acid, base, strong oxidation, strong reduction, metal catalysis, light, air, and moisture are not equivalent for all substrates. Whether a method is suitable depends first on whether the existing functional groups on the substrate can tolerate the relevant conditions.
(3) Then determine whether there are already usable reaction handles
If the molecule already contains existing reaction handles such as halides, boronate esters, alkenes, or carbonyl groups, it is often more direct to first compare conventional polar reactions or cross-coupling strategies. If the molecule already contains a usable directing group, then it is worth evaluating whether directed C-H functionalization should be introduced. If no preinstalled handle is available, the next step is to compare the feasibility of two routes: prefunctionalization followed by transformation, or direct site-selective functionalization.
(4) Finally, consider which stage of the route the current intermediate belongs to
Early-stage intermediates usually tolerate harsher conditions or skeletal modification more readily. Late-stage intermediates, by contrast, often place greater emphasis on functional group compatibility, site selectivity, and simple workup. The closer a molecule is to the final product, the higher the usual requirement for tolerance toward imperfect conditions.
Protection and deprotection steps are not forbidden, but they should not be the default starting point or the first option considered. Only when key sites truly interfere with the main transformation and no shorter route is available does the introduction of protecting groups become genuinely meaningful.
3. Use the target structure to determine the preferred class of methods
After evaluating the substrate, the analysis must return to the target structure. The target structure does not simply determine “which functional group must be installed in the end”; it determines which class of methods should be considered first.
Target Structure Feature | Priority Question | Preferred Methods |
The framework is already in place, and only the functional group form is missing | Can the target be reached through a small number of functional group interconversions? | Oxidation, reduction, substitution, elimination, addition, hydrolysis, esterification, amidation |
A key connection is missing | Should the new bond be formed early in the route, or assembled later? | Nucleophilic addition, condensation, substitution, cross-coupling |
The target series requires rapid fragment replacement | Is modular assembly needed? | Cross-coupling, fragment-based assembly |
The target requires late-stage local modification | Is it worth installing a handle in advance for a single site? | Photoredox catalysis, C-H functionalization |
The target involves changes in ring system or chain length | Is skeletal modification required rather than simple functional group adjustment? | Cyclization, ring opening, rearrangement, homologation |
The key at this stage is to first identify the transformation type that lies closest to the endpoint. If the target can be reached in two routine functional group interconversions, there is no need to introduce a higher-barrier method prematurely. If the target itself requires rapid fragment replacement, the value of cross-coupling rises substantially.
4. Preferred order for screening conventional synthetic routes
In the absence of clear structural limitations, convergence advantages, or process constraints, synthetic routes can usually be screened in an order from simpler to more complex. The benefit of this approach is that it allows one to compare methods with clearer operating conditions and more mature workup procedures first, and only then decide whether reaction systems with stricter requirements need to be introduced.
(1) First ask whether functional group interconversion can solve the problem
If the target framework is already present and only the functional group type or oxidation state is incorrect, functional group interconversion is usually the shortest and most direct route. Such steps are often logically straightforward, analytically simpler, and relatively easier to control upon scale-up.
(2) If functional group interconversion is not enough, then examine classical polar bond-forming reactions
When the target molecule lacks a clearly defined connection, priority should be given to classical polar reactions such as nucleophilic addition, substitution, condensation, acylation, and amination. The key questions for this class of methods are: which partner is the nucleophile, which is the electrophile, where side reactions may arise, and how stereochemistry can be controlled.
(3) If modular assembly is needed, then consider cross-coupling
The central value of cross-coupling lies in converting a linear route into a fragment-based assembly strategy. For targets that require rapid replacement of aryl, heteroaryl, alkenyl, or other defined fragments, this modular advantage is highly significant.
(4) When route length or structural complexity becomes a clear limitation, consider skeletal modification steps
Cyclization, rearrangement, ring opening, and homologation are all extremely important in total synthesis and in the construction of complex frameworks, but they are better deployed at points where they can clearly reshape route length and structural complexity, rather than being treated as the default starting method.
5. When to introduce expanded reaction platforms
When conventional routes cannot solve the problem efficiently, methods such as cross-coupling, photoredox catalysis, and C-H functionalization should be treated as priority options.
(1) Cross-coupling: when fragment-based assembly matters more than linear progression
If the target series requires frequent fragment replacement, or if the two fragments can each be prepared reliably on their own, cross-coupling can often significantly improve route flexibility. Its particular strength lies in modular assembly.
(2) Photoredox catalysis: when a single-electron pathway or mild radical conditions are needed
Photoredox catalysis relies on photoexcitation of the catalyst system to enter a single-electron regime. It is well suited to transformations that require mild radical generation, proceed through single-electron pathways, or are difficult to realize through conventional nucleophile-electrophile logic. It is useful for late-stage modification, radical bond formation, and scenarios in which redox processes are coupled with bond-forming events. At the same time, the wavelength and intensity of the light source, the reactor, light transmission efficiency, reaction mixture color, and the influence of oxygen can all significantly change the outcome.
(3) C-H functionalization: when the cost of prefunctionalization is too high
The most attractive feature of C-H functionalization is the possibility of bypassing the back-and-forth sequence of “install a reaction handle first, then carry out the transformation,” thereby compressing the route. The core questions for these methods are whether site selectivity has a sound basis, whether substrate compatibility is sufficient, and whether the relevant conditions are mature enough. It is not the default first choice, but it becomes more worthy of priority consideration when the cost of prefunctionalization is clearly too high and when site selectivity is supported by a clear rationale.
6. Reaction selection must ultimately be grounded in experimental conditions
Route design cannot stop at “methodologically feasible.” What often determines experimental success are condition compatibility, workup difficulty, and scale-up feasibility.
Evaluation Dimension | What Must Be Confirmed | Common Consequences |
Chemoselectivity | Will other functional groups undergo competing reactions? | Lower yield, increased by-products |
Site selectivity | Is the target site sufficiently differentiated? | Mixed isomers, difficult purification |
Stereochemistry | Is there a risk of racemization, configurational inversion, or diastereomeric issues? | The entire downstream sequence is affected |
Condition compatibility | Can the substrate tolerate acid/base, redox conditions, light, air, and moisture? | The reaction cannot be advanced reproducibly |
Availability of the catalytic system | Are the catalyst, ligand, oxidant, and additives readily available and reusable? | Feasible in the literature, but difficult to reproduce experimentally |
Workup difficulty | Are quenching, metal removal, decolorization, and separation straightforward? | Feasible on small scale, but blocked in scale-up |
Safety and scale-up | What are the risks associated with exotherms, gas evolution, photochemical scale-up, and strong oxidants? | The route must be redesigned |
For photoredox chemistry, the light source and reactor are part of the reaction conditions rather than auxiliary accessories. For cross-coupling, the catalyst, ligand, base, and metal-removal step are often equally critical. For C-H functionalization, site selectivity and substrate compatibility are usually more important to evaluate first than the isolated yield alone.
7. A practical sequence for route screening
The considerations above can be organized into a practical screening sequence for real-world use. When designing a route, the following seven steps can be applied in order.
1. First determine whether the current problem is one of functional group interconversion, bond construction, or skeletal modification.
2. Then identify which sites on the substrate must be preserved and which functional groups are sensitive to the reaction conditions.
3. Give priority to functional group interconversions that can move the intermediate directly closer to the target structure.
4. If a new connection must be formed, first compare classical polar bond-forming methods, and then compare whether cross-coupling is needed.
5. If prefunctionalization would clearly lengthen the route, then evaluate whether C-H functionalization is worth introducing.
6. If conventional two-electron pathways are difficult to advance, then assess whether photoredox catalysis can provide a new reaction channel.
7. Finally, judge the route on the basis of condition compatibility, workup, safety, and scale-up feasibility.
8. Navigation Table of Representative Chemicals Related to Reaction Selection in Small-Molecule Synthesis (Choose Table 1 to Table 5 by Research or Experimental Goal)
Research or Experimental Goal | Recommended Table to Consult First | Why Start with This Table | Recommended Tables to Cross-Reference | Navigation Guidance |
The target framework is already available, and the goal is to complete functional group interconversion without altering the framework | Table 1 | Table 1 focuses on oxidation, reduction, and selective functionalization reagents, making it suitable for first determining whether the current step involves oxidation-state adjustment, functional group replacement, or local functionalization | Table 2 | First assess whether the transformation can be completed through direct oxidation-reduction or selective functionalization; if the substrate contains amine, acid, alcohol, or related sites, Table 2 can then be used to evaluate protection, deprotection, or activation steps |
Carboxylic acids, amines, alcohols, or related starting materials need to be connected to construct amides, esters, ureas, carbonates, or similar bond types | Table 2 | Table 2 covers carboxylic acid activation, coupling, protection/deprotection, and organic bases, making it suitable for first evaluating condensation pathways and the relevant condition window | Tables 1 and 3 | First determine whether direct condensation is feasible or whether protection followed by coupling is required; if the target molecule will require further fragment assembly later, Table 3 can then be consulted to plan cross-coupling steps |
The target molecule lacks a key aryl, heteroaryl, or alkenyl fragment and must be assembled in a modular manner | Table 3 | Table 3 focuses on commonly used cross-coupling substrates, palladium sources, copper salts, and phosphine ligands, making it suitable for first evaluating whether Suzuki coupling, amination, or other coupling routes should be used | Tables 2 and 5 | If boronate ester installation, amine protection, or substrate activation is needed before coupling, Table 2 can be consulted; if preinstalled reaction handles are to be avoided, the C-H functionalization routes in Table 5 can also be compared |
The substrate already contains multiple sensitive functional groups, and the goal is to complete late-stage modification or radical bond formation under relatively mild conditions | Table 4 | Table 4 focuses on visible-light photoredox catalysts, electron-transfer reagents, and organic hydrogen donors, making it suitable for first evaluating whether a transformation can be enabled through a single-electron pathway | Tables 1 and 5 | If the target only requires localized redox adjustment, it can first be compared with conventional routes in Table 1; if directing-group-assisted or metal-mediated site activation is involved, Table 5 can also be consulted |
Halogenation, borylation, or other prefunctionalization steps are to be avoided, and the goal is to directly modify an existing arene, heteroarene, or alkenyl site | Table 5 | Table 5 focuses on metal systems, oxidants, and carboxylic acid additives commonly used in C-H functionalization, making it suitable for first evaluating whether direct site-selective transformation is possible | Tables 3 and 4 | If direct activation is too difficult, one may return to Table 3 and choose a route involving prefunctionalization followed by coupling; if the target transformation is better suited to a radical pathway, it can also be compared with Table 4 |
At an early stage of route design, there is a need to quickly compare two strategies: “functional group interconversion first” versus “bond construction first, modification later” | Table 1 | Table 1 helps first determine whether the existing intermediate can be brought closer to the target structure through direct oxidation, reduction, or selective functionalization | Tables 3 and 2 | If the direct transformation requires fewer steps, Table 1 can be followed first; if the target lacks a key connection, Table 3 should then be considered; if protection and condensation are interspersed in the route, Table 2 should also be consulted |
Multiple feasible routes exist for the same target molecule, and there is a need to compare conventional polar pathways with radical pathways | Tables 1 and 4 | Table 1 represents conventional functional group interconversion logic, while Table 4 represents light-driven single-electron logic; comparing the two helps clarify the difference in reaction modes | Tables 3 and 5 | If neither pathway directly solves the key bond-forming problem, Table 3 can be consulted further; if shortening prefunctionalization steps is desired, Table 5 can then be compared |
The project is in the method-development stage, and the goal is to screen conditions around catalytic systems rather than fix a single route from the outset | Tables 3, 4, and 5 | These three tables correspond respectively to cross-coupling, photoredox catalysis, and C-H functionalization, making them suitable for separate screening by reaction mode | Tables 1 and 2 | After the catalytic system has been selected, return to Tables 1 and 2 to complete substrate pretreatment, subsequent functional group interconversion, or protection/deprotection planning |
Sensitive fragments will only be introduced at a late stage of the target molecule, so the goal is to build the framework first and fine-tune it later | Table 3 | Table 3 is suitable for completing fragment assembly and framework construction first, making it easier to leave high-risk functional groups for later-stage processing | Tables 1 and 4 | After the framework has been assembled, Table 1 can be used for fine functional group adjustment; if late-stage modification requires high functional group compatibility, Table 4 can also be consulted |
The aim is to reduce route complexity from the standpoint of spectral analysis, separation, and workup | Tables 1 and 2 | The reaction types represented by these two tables are often easier to optimize from the standpoint of intermediate analysis, protection strategy, and control of condensation by-products | Table 3 | If cross-coupling must be used, Table 3 can then be revisited to choose more familiar substrate combinations and catalytic systems, thereby reducing the workup burden |
Table 1 | Oxidation, Reduction, and Selective Functionalization Reagents for Functional Group Interconversion
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Strong reducing agent | 16853-85-3 | L432195 | Lithium aluminium hydride (LAH) | suitable for synthesis, powder | A strong hydride reducing agent for deep reduction of esters, acids, amides, nitriles, and related substrates; commonly used in early-stage route steps for framework simplification and functional group rollback |
Mild reducing agent | 16940-66-2 | S432207 | Sodium borohydride | purum p.a., ≥96% | A mild reducing agent suitable for the reduction of aldehydes, ketones, and some imines or activated carbonyl compounds; appropriate for condition screening with multifunctional substrates |
Catalytic oxidation reagent | 2564-83-2 | TEMPO | sublimed grade, ≥99% | A stable nitroxyl radical used for the selective oxidation of alcohols; it can also participate in electrochemical or photoredox radical transformations | |
Hypervalent iodine oxidant | 87413-09-0 | Dess-Martin Periodinane (DMP) | ≥96% | A mild hypervalent iodine oxidant for converting primary and secondary alcohols into aldehydes and ketones; suitable for late-stage transformations of substrates containing multiple functional groups | |
Peracid oxidant | 937-14-4 | 3-Chloroperoxybenzoic acid (MCPBA) | ≥85% | Commonly used for alkene epoxidation, sulfide oxidation, and Baeyer-Villiger oxidation; a widely used oxidation tool in functional group interconversion | |
Hypervalent iodine oxidant | 3240-34-4 | Iodobenzene diacetate (DIB) | ≥98% | A hypervalent iodine oxidant that can be used in alcohol oxidation, deprotection, rearrangement, and radical oxidation steps; it can also serve as an oxidant in certain hypervalent iodine-mediated transformations | |
Electrophilic fluorinating / nitrogen-transfer reagent | 133745-75-2 | N-Fluorobenzenesulfonimide (NFSI) | ≥97% | Can be used for electrophilic fluorination, amination, and radical functionalization; suitable for reaction design requiring comparison between oxidative pathways and functional group installation pathways | |
Electrophilic fluorinating reagent / oxidant | 140681-55-6 | N-Fluoro-N'-(chloromethyl)triethylenediamine Bis(tetrafluoroborate) | ≥95% | A commonly used electrophilic fluorinating reagent that can also serve as an oxidant in radical activation and certain C-H functionalization systems |
Table 2 | Carboxylic Acid Activation, Amidation, Protection/Deprotection, and Organic Bases
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Strong-acid deprotection reagent | 76-05-1 | Trifluoroacetic acid (TFA) | anhydrous, ≥99% | A commonly used strong-acid deprotection reagent for tert-butoxycarbonyl removal, treatment of acid-sensitive intermediates, and preparation of amine salts | |
Hindered organic base | 7087-68-5 | N,N-Diisopropylethylamine | distilled grade, ≥99.5% | A hindered organic base used as an acid scavenger or electron donor in amidation, coupling, and photoredox systems | |
Acyl-transfer catalyst | 1122-58-3 | 4-Dimethylaminopyridine | ≥99% | An acyl-transfer catalyst used in esterification, acylation, carbonate formation, and transformations of activated carboxylic acid derivatives | |
Carbodiimide coupling reagent | 538-75-0 | N,N′-Dicyclohexylcarbodiimide | ≥99% | A dehydrative coupling reagent used for coupling carboxylic acids with amines or alcohols; also commonly used in the construction of anhydrides, lactams, and related structures | |
Carbonyl-activation reagent | 530-62-1 | N,N'-Carbonyldiimidazole (CDI) | ≥99% | Activates carboxylic acids, alcohols, and amines to generate acyl imidazole or carbonylated intermediates for amidation, esterification, urea formation, and cyclization reactions | |
Uronium coupling reagent | 148893-10-1 | HATU | ≥99% | Commonly used for amide bond formation when substrates are sterically hindered or when high coupling efficiency is required | |
Amine protecting reagent | 24424-99-5 | Di-tert-butyl dicarbonate | ≥99% | A commonly used amine protecting reagent for selective protection of amino groups, facilitating separation of reactive sites in multistep routes | |
Uronium coupling reagent | 94790-37-1 | HBTU | ≥99% | A commonly used amidation reagent for coupling carboxylic acids with amines and for rapid condensation in multistep routes | |
Water-soluble carbodiimide coupling reagent | 25952-53-8 | N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride | ≥98% | A water-soluble coupling reagent used for amidation, esterification, and condensation systems where cleaner workup is desired | |
Phosphonium coupling reagent | 128625-52-5 | 1H-Benzotriazol-1-yloxytripyrrolidinophosphonium Hexafluorophosphate | ≥98% | A phosphonium coupling reagent used for amide bond formation and condensation reactions of sterically hindered substrates |
Table 3 | Common Substrates, Metal Catalysts, and Ligands for Cross-Coupling
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Copper catalyst | 7681-65-4 | Copper(I) iodide | anhydrous, ≥99.995% metals basis | Used in Ullmann-type coupling, alkynylation, and cross-coupling systems operating cooperatively with palladium; it can also participate in certain photochemical or radical transformations | |
Palladium(II) precatalyst | 3375-31-3 | Palladium(II) acetate (47% Pd) | suitable for synthesis | A commonly used palladium precatalyst that can be combined with phosphine ligands for Suzuki coupling, Buchwald-Hartwig amination, the Heck reaction, and some C-H functionalization systems | |
Aryl bromide substrate | 108-86-1 | Bromobenzene | Standard for GC, ≥99.5% (GC) | A representative aryl bromide substrate for condition exploration in Suzuki coupling, Ullmann-type coupling, Grignard reagent coupling, and related transformations | |
Palladium(0) precatalyst | 14221-01-3 | Tetrakis(triphenylphosphine)palladium(0) | Pd ≥8.9% | A palladium(0) precatalyst that can be used directly in cross-coupling reactions such as Suzuki, Stille, and Sonogashira coupling | |
Palladium(0) source | 51364-51-3 | Tris(dibenzylideneacetone)dipalladium(0) | ≥99.95% metals basis | An active palladium source that can be combined with monophosphine or diphosphine ligands for developing carbon-nitrogen, carbon-carbon, and carbon-oxygen coupling conditions | |
Organoboron coupling substrate | 98-80-6 | Phenylboronic acid (PBA) (contains varying amounts of Anhydride) | ≥99.5% | A commonly used organoboron substrate for Suzuki coupling, oxidation to phenols, and studies of boronic acid derivative transformations | |
Diphosphine ligand | 12150-46-8 | 1,1'-Bis(diphenylphosphino)ferrocene (DPPF) | ≥99% | A commonly used diphosphine ligand that forms stable catalytic systems with palladium and other metals for cross-coupling and reductive coupling condition screening | |
Borylation reagent | 73183-34-3 | Bis(pinacolato)diboron | ≥99% | A commonly used borylation reagent for borylation, metal-catalyzed borylation, and the preparation of precursors for subsequent Suzuki coupling | |
Aryl iodide substrate | 591-50-4 | Iodobenzene | ≥99% | A relatively reactive aryl iodide substrate for evaluation of coupling, metalation, and radical arylation conditions | |
Diphosphine ligand | 98327-87-8 | 2,2′-Bis(diphenylphosphino)-1,1′-binaphthalene | ≥98% | A commonly used diphosphine ligand for palladium-, rhodium-, and ruthenium-catalyzed coupling, as well as screening of asymmetric catalytic conditions | |
Buchwald-type monophosphine ligand | 787618-22-8 | 2-Dicyclohexylphosphino-2′,6′-diisopropoxybiphenyl | ≥98% | Used in palladium-catalyzed carbon-nitrogen and carbon-oxygen bond formation, including some relatively difficult coupling substrates | |
Buchwald-type monophosphine ligand | 657408-07-6 | 2-Dicyclohexylphosphino-2′,6′-dimethoxybiphenyl | ≥98% | Used in cross-coupling reactions such as Suzuki coupling and Buchwald-Hartwig amination; suitable for comparing the influence of steric and electronic effects on catalytic activity | |
Buchwald-type monophosphine ligand | 1070663-78-3 | Dicyclohexyl(2',4',6'-triisopropyl-3,6-dimethoxy-[1,1'-biphenyl]-2-yl)phosphine | ≥97% | Used for carbon-nitrogen and carbon-oxygen coupling of relatively difficult-to-activate substrates such as aryl chlorides | |
Buchwald-type monophosphine ligand | 564483-18-7 | 2-Dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (X-Phos) | ≥97% | Commonly used in Suzuki coupling, Buchwald-Hartwig amination, and certain carbon-sulfur bond-forming systems |
Table 4 | Visible-Light Photoredox Catalysts and Electron-Transfer Reagents
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Iridium photocatalyst | 94928-86-6 | Tris[2-phenylpyridinato-C2,N]iridium(III) | sublimed grade | A classic iridium photocatalyst for condition screening in radical addition, dehalogenation, and cross-coupling enhancement | |
Ruthenium photocatalyst | 50525-27-4 | Tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate | ≥99.95% metals basis | A classic ruthenium photocatalyst for visible-light condition exploration in oxidative-quenching or reductive-quenching radical reactions | |
Organic photocatalyst | 1416881-52-1 | 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene | ≥99% (HPLC) | An organic photoredox catalyst for metal-free reductive or oxidative transformations, decarboxylative coupling, and late-stage functionalization | |
Iridium photocatalyst | 870987-63-6 | (4,4'-Di-tert-butyl-2,2'-bipyridine)bis[3,5-difluoro-2-[5-trifluoromethyl-2-pyridinyl-κN)phenyl-κC]iridium(III) Hexafluorophosphate | ≥99% | A strongly oxidizing iridium photocatalyst suitable for activation of substrates with high oxidation potentials, radical addition, and late-stage functionalization | |
Organic reductant / hydrogen donor | 1149-23-1 | Diethyl 1,4-Dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate | ≥98% (HPLC) | A commonly used organic hydrogen donor for photoredox reductive-quenching systems, dehalogenation, reductive coupling, and hydrogen-atom transfer processes | |
Organic photocatalyst | 1442433-71-7 | 9-Mesityl-10-methylacridinium tetrafluoroborate | ≥97% | An organic photocatalyst for anti-Markovnikov hydrofunctionalization of alkenes, oxidative radical addition, and late-stage functionalization | |
Organic dye photocatalyst | 15086-94-9 | Eosin Y (AMI-5) | ≥95% | An organic dye photocatalyst for visible-light radical addition, reductive dehalogenation, and oxidative coupling | |
Organic dye photocatalyst | 632-69-9 | Rose bengal | ≥95% | An organic dye photosensitizer for transformations involving singlet oxygen, oxidative conversion, and visible-light radical processes |
Table 5 | Common Metal Systems, Oxidants, and Additives for C-H Functionalization and Advanced Catalytic Transformations
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
External oxidant | 7727-21-1 | Potassium persulfate | analytical grade, ≥99.5% | A commonly used external oxidant for radical oxidation, decarboxylation, sulfate radical generation, and certain photoredox or C-H functionalization systems | |
Ruthenium precatalyst | 14898-67-0 | Ruthenium(III) chloride hydrate | suitable for analysis, premium grade | A ruthenium precatalyst for oxidation, transfer hydrogenation, and some ruthenium-catalyzed C-H functionalization systems | |
Copper salt oxidant / additive | 6046-93-1 | Copper(II) acetate monohydrate | suitable for analysis, ACS, premium grade | A commonly used copper salt oxidant or additive for oxidative coupling, Chan-Lam coupling, and certain reoxidation steps in C-H activation | |
Pentamethylcyclopentadienyl rhodium precatalyst | 12354-85-7 | C431633 | Chiralyst P618 | Umicore | Commonly used in directing-group-assisted C-H functionalization of arenes, alkenes, and heteroarenes, and also in rhodium-catalyzed cyclization and insertion reactions |
Rhodium salt precatalyst | 20765-98-4 | Rhodium Chloride Hydrate | Rh 38.5-42.5% | A rhodium salt precatalyst for oxidation, addition, and some rhodium-catalyzed C-H activation and cyclization systems | |
Silver salt additive | 563-63-3 | Silver acetate | AR, ≥99.5% | A commonly used silver salt additive for halide abstraction, reoxidation, and promotion of certain C-H activation steps | |
Carboxylic acid additive | 75-98-9 | Pivalic acid (PA) | ≥99% | A commonly used carboxylic acid additive that can promote metalation and deprotonation steps in certain C-H activation systems and can also modulate catalytic activity | |
Pentamethylcyclopentadienyl iridium precatalyst | 12354-84-6 | Pentamethylcyclopentadienyliridium(III) chloride,dimer | ≥98% | An iridium precatalyst for directing-group-assisted C-H activation, alkene insertion, and oxidative coupling | |
Arene ruthenium precatalyst | 52462-29-0 | Dichloro(p-cymene)ruthenium dimer | ≥97% (T) | A ruthenium precatalyst for transfer hydrogenation, C-H activation of alkenes or arenes, and cyclization reactions |
Note: The products above are representative Aladdin products. For additional product specifications, search by “product name/CAS/catalog number” on the Aladdin website.
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