Hubbry Logo
BINAPBINAPMain
Open search
BINAP
Community hub
BINAP
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
BINAP
BINAP
BINAP
View on Wikipedia
from Wikipedia
BINAP
Names
Preferred IUPAC name
([1,1′-Binaphthalene]-2,2′-diyl)bis(diphenylphosphane)
Other names
BINAP
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.114.880 Edit this at Wikidata
EC Number
  • 616-304-7

    619-338-0 616-305-2

    918-620-3
UNII
  • InChI=1S/C44H32P2/c1-5-19-35(20-6-1)45(36-21-7-2-8-22-36)41-31-29-33-17-13-15-27-39(33)43(41)44-40-28-16-14-18-34(40)30-32-42(44)46(37-23-9-3-10-24-37)38-25-11-4-12-26-38/h1-32H ☒N
    Key: MUALRAIOVNYAIW-UHFFFAOYSA-N ☒N
  • (Rac): c1ccc(cc1)P(c2ccccc2)c3ccc4ccccc4c3c5c6ccccc6ccc5P(c7ccccc7)c8ccccc8
Properties
C44H32P2
Molar mass 622.688 g·mol−1
Appearance Colorless solid
Melting point 239 to 241 °C (462 to 466 °F; 512 to 514 K) (R)
238–240 °C (S)
organic solvents
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335, H413
P261, P264, P271, P273, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Ball and stick model of BINAP viewed as above

BINAP (2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) is an organophosphorus compound. This chiral diphosphine ligand is widely used in asymmetric synthesis. It consists of a pair of 2-diphenylphosphinonaphthyl groups linked at the 1 and 1′ positions. This C2-symmetric framework lacks a stereogenic atom, but has axial chirality due to restricted rotation (atropisomerism). The barrier to racemization is high due to steric hindrance, which limits rotation about the bond linking the naphthyl rings. The dihedral angle between the naphthyl groups is approximately 90°. The natural bite angle is 93°.[1]

Use as ligand in asymmetric catalysis

[edit]

BINAP is used in organic synthesis for enantioselective transformations catalyzed by its complexes of ruthenium, rhodium, and palladium.[2] As pioneered by Ryōji Noyori and his co-workers, rhodium complexes of BINAP are useful for the synthesis of (–)-menthol.[3][4]

Silver complexes are also important; BINAP-AgF can be used to enantioselectively protonate silyl enol ethers.[5]

Subsequent studies revealed that related diphosphines with a narrower dihedral angle between the aromatic faces give catalysts that are more enantioselective. One such ligand is SEGPHOS.[6]

Preparation

[edit]

BINAP is prepared from BINOL[7][8] via its bistriflate derivatives. Both the (R)- and (S)-enantiomers, as well as the racemate, are commercially available. One of the wide applications include chemoselective hydrogenation, where BINAP is conjugated to rhodium.

Further reading

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

BINAP

View on Grokipedia
from Grokipedia
BINAP, or 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, is an axially chiral C2-symmetric renowned for its role in transition-metal-catalyzed asymmetric synthesis. First synthesized in 1974 by Ryoji Noyori and Hidemasa Takaya at , with optically active forms resolved by 1976 and the initial publication appearing in 1980, BINAP features a rigid binaphthyl backbone that imparts steric control for high enantioselectivity in catalytic reactions. The ligand's versatility stems from its ability to form stable complexes with metals such as , , and , enabling efficient asymmetric transformations. In , BINAP- complexes achieve up to 100% enantiomeric excess (ee) in the synthesis of from enamides, while BINAP- catalysts β-keto esters and allylic alcohols with >99% ee, facilitating industrial production of pharmaceuticals like naproxen. Beyond , BINAP promotes enantioselective of allylic amines for (-)- synthesis (96–99% ee, >1500 tons annually) and carbon-carbon bond formations such as the . Noyori's work with BINAP contributed to his 2001 , shared with S. Knowles and K. Barry Sharpless, for pioneering chiral catalysis that has transformed the efficient, scalable production of enantiomerically pure compounds essential in and fine chemicals. Its enduring impact is evident in derivatives like SEGPHOS and numerous commercial applications, underscoring BINAP's status as a cornerstone of modern stereoselective synthesis.

Structure and properties

Molecular structure

BINAP, or 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, exists as stable (R)- and (S)-enantiomers due to its arising from atropisomerism, a consequence of the restricted rotation around the central C(1)–C(1') bond in the binaphthyl core. This stereogenic axis is maintained by the bulky rings fused to the framework, creating a high rotational energy barrier that prevents at room temperature. The of BINAP is C₄₄H₃₂P₂, reflecting the binaphthyl backbone substituted with two diphenylphosphino (PPh₂) groups at the peri positions (2 and 2'). The molecular architecture features two units linked at their 1 and 1' positions, with the PPh₂ moieties projecting outward from the 2 and 2' sites, forming a C₂-symmetric that is ideal for bidentate coordination to metals. The between the two naphthyl planes is approximately 90°, which contributes to the ligand's twisted conformation and influences its steric environment in complexes. This angle arises from the balance of steric repulsion between the ortho substituents on the naphthyl rings and the conjugative stabilization of the biaryl system. In metal complexes, the diphosphine adopts a bite angle of about 93°, defined as the P–M–P angle in chelates, which is relatively wide compared to smaller diphosphines and promotes specific geometries favorable for catalysis. This value, measured in structures like [PdCl₂(BINAP)], underscores how the ligand's backbone rigidity and phosphine separation optimize trans-spanning coordination. Compared to achiral analogs like BIPHEP (2,2'-bis(diphenylphosphino)-1,1'-biphenyl), BINAP's extended naphthalene rings impose greater steric bulk, elevating the atropisomerization barrier to ensure stable enantiopurity, whereas BIPHEP racemizes rapidly due to its more flexible biphenyl core.

Physical and chemical properties

BINAP appears as a to off-white crystalline solid. Its molecular formula is C44H32P2, with a of 622.67 g/mol. The compound exhibits enantiomer-specific melting points: 239–241 °C for the (R)- and 238–240 °C for the (S)-. BINAP demonstrates high solubility in common organic solvents such as , , and , with modest solubility in , , and ; it is insoluble in water. BINAP is air-stable under normal conditions, allowing for straightforward handling without the need for inert atmospheres. However, the groups are susceptible to oxidation to phosphine oxides upon prolonged exposure to oxygen, particularly in solution. Chemically, BINAP acts as a bidentate , readily forming stable coordination complexes with transition metals through σ-donation from its atoms, but it exhibits no catalytic activity on its own. The enantiomers display characteristic optical rotations, such as [α]20D +222° (c = 0.5 in ) for (R)-BINAP and the corresponding negative value for the (S)-.

History and development

Discovery

BINAP, or 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, was first synthesized in 1974 by Ryōji Noyori and Hidemasa Takaya at in , with optically active forms resolved by 1976; its first report appeared in 1980. The development stemmed from efforts to create more effective chiral bidentate ligands for transition-metal , particularly to enhance enantioselectivity in rhodium-catalyzed reactions. Earlier ligands, such as DIOP introduced by Kagan in 1971, had achieved moderate optical yields (typically up to 80% enantiomeric excess) but suffered from limitations in chiral recognition and catalytic efficiency for certain substrates. Noyori's team sought a ligand with and a rigid framework to provide superior steric control and stability in catalytic complexes. The initial synthesis of enantiomerically pure BINAP began with optically active 1,1'-bi-2-naphthol (BINOL), which was deprotonated via dilithiation using to form the dianion, followed by reaction with chlorodiphenylphosphine to introduce the phosphino groups at the 2,2'-positions. This method yielded the atropisomeric with high stereochemical integrity due to the restricted rotation in the binaphthyl backbone. The first report of this synthesis and its application appeared in a communication in the Journal of the , where the authors detailed the preparation of (R)-BINAP and its coordination to (I) to form cationic complexes. These BINAP-Rh(I) catalysts demonstrated exceptional performance in the of α-(acylamino)acrylic acids and esters, such as α-acetamidocinnamic acid derivatives, achieving enantiomeric excesses exceeding 95% under mild conditions (1 H₂, ). This breakthrough laid the foundation for BINAP's role as a versatile in asymmetric . The ligand's effectiveness in promoting highly enantioselective reductions marked a significant advancement over prior diphosphine systems, enabling practical synthesis of chiral and related compounds. Noyori's contributions to this field, including the invention and application of BINAP, were recognized with the 2001 , shared with William S. Knowles for their pioneering work on chirally catalyzed hydrogenation reactions.

Key developments

In 1986, H. Takaya and colleagues at Nagoya University reported the first practical large-scale synthesis of enantiomerically pure BINAP, starting from binaphthol and involving a key Ullmann coupling followed by phosphination and resolution via diastereomeric salt formation. This breakthrough overcame earlier challenges in producing gram-scale quantities of the chiral ligand, enabling its commercial availability through suppliers like Takasago International Corporation and facilitating broader adoption in asymmetric catalysis. During the 1990s, R. Noyori extended BINAP's utility by developing complexes for the of ketones, particularly β-keto esters, achieving enantioselectivities exceeding 99% ee under mild conditions (e.g., 1 H₂, ). These Ru-BINAP-dihalide or dicarboxylate catalysts marked a significant advancement over rhodium-based systems, expanding BINAP's scope to unfunctionalized and functionalized carbonyls while maintaining high turnover numbers (up to ). BINAP's industrial adoption accelerated in the late , exemplified by its use in the large-scale production of (S)-naproxen, a , via Ru-BINAP-catalyzed at . This process replaced classical resolution methods, reducing waste and costs while yielding >99% on multi-ton scales, demonstrating BINAP's economic viability in . The versatility of BINAP across transition metals—rhodium for olefin hydrogenations, ruthenium for ketone reductions, and palladium for cross-couplings—was a cornerstone of Noyori's 2001 , shared with W. S. Knowles for pioneering chirally catalyzed hydrogenations. This recognition underscored BINAP's role in enabling stereoselective syntheses with minimal catalyst loadings (0.01–1 mol%). In recent years, BINAP has been integrated into continuous-flow processes for enhanced scalability and safety, such as Ru-BINAP-catalyzed hydrogenations in microreactors, achieving yields >95% with reduced reaction times compared to batch methods. These developments reflect ongoing refinements rather than paradigm shifts, maintaining BINAP's status as a benchmark ligand.

Synthesis

Preparation methods

BINAP is prepared from 1,1'-bi-2-naphthol (BINOL), which is commercially available in both racemic and enantiopure forms. The standard synthetic route to both racemic and enantiopure BINAP involves initial conversion of BINOL to 2,2'-bis(trifluoromethanesulfonyloxy)-1,1'-binaphthyl (bis-triflate) by treatment with triflic anhydride in the presence of a base such as or triethylamine. This electrophilic activation of the phenolic hydroxy groups facilitates subsequent carbon-phosphorus bond formation. The bis-triflate then undergoes metal-catalyzed cross-coupling with diphenylphosphine (HPPh₂) or chlorodiphenylphosphine (ClPPh₂). For instance, palladium-catalyzed coupling of the bis-triflate with HPPh₂, using Pd(OAc)₂ or Pd₂(dba)₃ as the precatalyst along with a like dppp, proceeds under mild conditions (typically in DMF or at 80–100 °C) to afford BINAP directly after workup. Racemic BINAP is synthesized from achiral (racemic) BINOL via this bis-triflate route, often achieving isolated yields up to 90% for the step, though protection of the naphthol hydroxy groups may be incorporated in earlier stages if needed to prevent side reactions during scale-up. The multi-step process from BINOL typically delivers overall yields of 70–80%, making it suitable for industrial production. Enantiopure BINAP retains the of the starting enantiopure BINOL throughout, with no observed under these conditions. An alternative coupling variant employs nickel catalysis, such as NiCl₂(dppe) with HPPh₂ and as base, yielding 77–87% for the chiral ligand. The original 1980 method reported by Noyori and coworkers provides an alternative direct route without triflate activation: BINOL is treated with chlorodiphenylphosphine oxide (Ph₂P(O)Cl) in to form the bis(phosphine oxide) intermediate, which is isolated and then reduced with (HSiCl₃) in to yield BINAP in 85% from the intermediate (overall ~50–60% from BINOL due to earlier steps). This approach, while effective for laboratory scale, has been largely superseded by the higher-yielding triflate methods for production. Purification of BINAP commonly involves to remove byproducts formed during coupling or reduction, followed by recrystallization from solvents like or to achieve high purity (>99%).

Enantioselective synthesis

Enantiopure BINAP is essential for asymmetric , and its preparation typically involves resolution of racemic mixtures or direct synthesis from chiral precursors. Resolution of racemic BINAP or its precursors, such as the bis-phosphine oxide, is commonly achieved through diastereomeric salt formation using chiral resolving agents like dibenzoyl . Salt formation remains the prevalent method for BINAP. A seminal approach, reported by Takaya and coworkers in 1986, involves synthesizing the racemic bis-phosphine oxide from BINOL, followed by resolution via diastereomeric salt formation with (R,R)-dibenzoyl to isolate the enantiopure (S)- (yield ~45%). The resolved is then reduced using phenylsilane in the presence of a catalyst, affording enantiopure (S)-BINAP with >99% ee. This method established a practical route for both (R)- and (S)-BINAP, with the (R)-enantiomer obtained similarly using (S,S)-dibenzoyl after upgrading lower-purity fractions. Asymmetric synthesis from enantiopure BINOL represents a preferred modern route, bypassing resolution steps and directly yielding high enantiopurity. Enantiopure BINOL, obtained from chiral pool sources or asymmetric catalysis, is converted to the bis-triflate, which undergoes nickel-catalyzed cross-coupling with diphenylphosphine (Ph₂PH) to form BINAP in 77% yield and >99% . This approach maintains chiral integrity throughout, with overall efficiencies exceeding 95% . Commercial production of enantiopure BINAP, primarily by companies like Takasago International, scales these methods to yield grams to kilograms, supporting industrial asymmetric processes such as synthesis. Due to BINAP's atropisomeric nature, where the arises from restricted rotation about the biaryl bond, the exhibits high configurational stability under typical reaction conditions.

Applications in catalysis

Asymmetric hydrogenation

BINAP serves as a key chiral in and complexes for enantioselective reactions, particularly targeting prochiral alkenes and ketones to produce valuable chiral building blocks with high enantiomeric excess (ee). These systems leverage BINAP's to create a sterically biased environment around the metal center, enabling selective hydrogen delivery to one face of the substrate. In the rhodium-BINAP system, cationic Rh(I) complexes effectively hydrogenate α,β-unsaturated carboxylic acids and esters, such as in the conversion of methyl (Z)-acetamidocinnamate to the (S)- precursor with >95% under mild conditions. This application, first demonstrated in , marked a significant advancement in synthesizing optically active . Ruthenium-BINAP complexes extend this capability to the hydrogenation of β-ketoesters and imines, with notable in reducing simple ketones. For instance, Noyori's 1995 development using Ru(II) complexes with BINAP and chiral co-ligands enables the production of (R)-1,2-propanediol from hydroxyacetone with turnover numbers () up to 10,000 and >99%. A representative example is the hydrogenation of : \cePhC(O)CH3+H2−>[Ru−BINAP/diamine][H+]PhCH(OH)CH3\ce{PhC(O)CH3 + H2 ->[Ru-BINAP/diamine][H+] PhCH(OH)CH3} yielding (R)-1-phenylethanol with ee >99%. The mechanism in the Ru-BINAP system involves an outer-sphere pathway, where the chiral environment from BINAP's axial chirality, combined with the metal-ligand bifunctional activation of H₂ (as hydridic Ru-H and protic N-H), induces substrate facial selectivity without direct coordination of the ketone to the ruthenium center. This contrasts with inner-sphere mechanisms in some Rh systems. Compared to earlier ligands like DIPAMP, BINAP-based catalysts offer superior turnover numbers and broader substrate scope, particularly for unfunctionalized ketones, enabling industrial-scale applications.

Other asymmetric transformations

BINAP has been employed in palladium-catalyzed asymmetric Heck reactions, enabling the enantioselective arylation of alkenes to form chiral cyclic structures. For instance, intramolecular Heck cyclizations using Pd-BINAP complexes achieve high enantioselectivities, such as >90% in the synthesis of 2,3-dihydrobenzofurans from aryl iodides tethered to alkenes. Silver-BINAP complexes facilitate the enantioselective protonation of silyl enol ethers, providing access to α-chiral ketones under mild conditions. The AgF-BINAP system in dichloromethane-methanol at low temperatures protonates trimethylsilyl enol ethers derived from ketones like propiophenone, yielding products with up to 95% ee. Ruthenium-BINAP catalysts promote the asymmetric isomerization of allylic alcohols to enones, converting secondary allylic alcohols into chiral ketones with excellent enantiocontrol. This transformation, often using RuCl2(BINAP) complexes in basic media, routinely delivers >98% ee for a range of substrates. Notable applications include the Pd-BINAP-catalyzed asymmetric cyclization in the 1990s synthesis route to (-)- developed by , which constructs key chiral carbon centers via intramolecular coupling. BINAP also features in the preparation of taxol intermediates through enantioselective C-C bond formations, such as allylic substitutions that install stereocenters in the core. Beyond these, BINAP excels in other C-C bond-forming reactions, including palladium-catalyzed asymmetric allylic alkylations of enolates or amines, which proceed with 85-99% depending on the substrate. Rhodium-BINAP systems enable conjugate additions of arylboronic acids to α,β-unsaturated carbonyls, affording β-aryl products in >90% . However, BINAP shows reduced efficacy in certain allylic alkylations involving sterically hindered nucleophiles compared to more modern ligands like SEGPHOS derivatives.

Derivatives and analogs

Modified BINAP ligands

Modified BINAP ligands have been developed to address limitations of the parent compound, such as steric constraints, solubility issues, and substrate specificity in catalytic applications. These modifications typically involve alterations to the binaphthyl backbone or the substituents, enabling fine-tuning of electronic and steric properties for improved enantioselectivity and reaction scope. Axial modifications on the naphthyl rings, particularly at the 3,3'-positions, introduce substituents to adjust the ligand's steric environment. For instance, 3,3'-disubstituted BINAP derivatives with alkoxy or acetoxy groups have been synthesized through convergent routes involving resolution by , achieving high enantiopurity. These ligands enhance enantioselectivity in ruthenium-catalyzed asymmetric s, with the 3,3'-dimethoxy variant delivering up to 99% in the hydrogenation of 1,1-diarylalkenes, outperforming unmodified BINAP under identical conditions. Variations in the moieties replace the phenyl groups on with sulfonate groups to improve water , facilitating biphasic . Sulfonated BINAP (BINAS) is prepared by selective sulfonation of the phenyl rings, yielding highly water-soluble derivatives in 43% overall yield from BINAP. This modification enables rhodium-catalyzed asymmetric hydrogenations in aqueous media, achieving enantioselectivities comparable to the parent while allowing easy catalyst recovery through . Dendritic BINAP ligands incorporate multiple BINAP units into multi-generation structures, synthesized via allylation reactions of dendritic polyaryl ethers with BINAP precursors. These ligands form complexes that catalyze asymmetric hydrogenations of β-ketoesters with high efficiency and recyclability, recovering up to 90% of the catalyst after several runs without loss of enantioselectivity. The octahydro derivative, H₈-BINAP, features saturated naphthyl rings, increasing backbone flexibility and lipophilicity compared to BINAP. Developed by Hidemasa Takaya and coworkers in the mid-1990s, it is synthesized from H₈-BINOL analogs and excels in palladium-catalyzed allylation reactions, providing high enantioselectivities. Synthesis of these modified BINAP ligands generally proceeds through analogs of BINOL, the binaphthol precursor, followed by phosphination steps, with overall yields typically ranging from 60-80%. Certain derivatives achieve enantiomeric excesses exceeding 99.9% in targeted asymmetric transformations, effectively overcoming substrate limitations of unmodified BINAP in ruthenium and palladium catalysis. Related bidentate phosphine ligands, such as SEGPHOS and its variants, BIPHEP, P-Phos, and analogs like MOP, have been developed to complement BINAP by offering alternative structural features that enhance performance in specific asymmetric catalyses while addressing challenges like high cost and steric bulk associated with the naphthyl backbone. These ligands typically retain the C₂-symmetric diphosphine motif central to BINAP's success but incorporate modified biaryl backbones or hybrid designs for improved solubility, reactivity, or selectivity. Evolved primarily during the 1990s and 2000s, they enable broader applications in transition-metal catalysis, particularly for ruthenium and palladium systems. The SEGPHOS family, exemplified by the bulky derivative 4,4'-bis(1,1-dimethylethyl)-4,4',6,6'-tetramethyl-2,2'-bisphosphino-1,1'-biphenyl (DTBM-SEGPHOS), features a biaryl backbone with 1,3-benzodioxole units that confer a smaller of approximately 65° compared to BINAP's 73.5°, enhancing orbital overlap and enantiocontrol in metal complexes. Developed by Takasago researchers building on earlier work by Sawamura and Noyori, this excels in ruthenium-catalyzed asymmetric hydrogenations, achieving enantiomeric excesses up to 99.5% for β-ketoesters due to its electron-rich and sterically demanding environment. In industrial applications, such as the synthesis of naproxen, SEGPHOS variants surpass BINAP by delivering higher enantioselectivities (often >99%) and better catalyst efficiency, facilitating large-scale production of the anti-inflammatory drug. BIPHEP, or 2,2'-bis(diphenylphosphino)-1,1'-biphenyl, serves as an achiral analog of BINAP, lacking the fused naphthyl rings that enforce , and is frequently employed as a benchmark to evaluate the contributions of axial versus point in catalytic performance. Its flexible backbone allows easier rotation, making it less selective but useful for comparing reactivity profiles in achiral versus chiral environments, particularly in - and palladium-catalyzed processes. Unlike BINAP, BIPHEP's simpler structure reduces synthesis costs, highlighting trade-offs in steric control. P-Phos ligands, such as (S)-2,2',6,6'-tetramethoxy-4,4'-bis(diphenylphosphino)-3,3'-bipyridine, incorporate methoxy-substituted rings in an atropisomeric biaryl framework, providing bidentate coordination with tunable electronics for -catalyzed cross-couplings and allylations. Inspired by BINAP's , these ligands offer superior activity in C-C bond formations, often achieving higher turnover numbers than BINAP analogs due to the donors' influence on metal acidity. Meanwhile, the related monodentate MOP ligand, 2-(diphenylphosphino)-2'-methoxy-1,1'-binaphthyl, adapts BINAP's motif for single-point binding in systems, enabling high enantioselectivities (up to 98%) in allylic alkylations and hydrosilylations without the need for bidentate . In comparisons across these ligands, SEGPHOS variants demonstrate superior enantioselectivity in hydrogenations for certain substrates but exhibit reduced versatility compared to BINAP's broad substrate scope, while P-Phos and excel in palladium-mediated transformations where BINAP underperforms due to steric constraints. All share the core C₂-symmetric diphosphine architecture, yet their optimizations—such as narrower angles in SEGPHOS or hybrid heteroatoms in P-Phos—address BINAP's limitations in cost and specificity, expanding the toolkit for asymmetric synthesis.

References

  1. https://pubs.acs.org/doi/10.1021/ja00547a020
  2. https://www.nobelprize.org/uploads/2018/06/noyori-lecture.pdf
  3. https://pubs.acs.org/doi/10.1021/ar00178a005
  4. https://www.nobelprize.org/prizes/chemistry/2001/noyori/facts/
  5. https://www.pnas.org/doi/10.1073/pnas.0307620101
  6. https://pubs.acs.org/doi/10.1021/cr040652w
  7. https://www.medchemexpress.com/s-binap.html
  8. https://www.sigmaaldrich.com/US/en/product/aldrich/693065
  9. https://www.synthesiswithcatalysts.com/product-details/s-binap
  10. https://onlinelibrary.wiley.com/doi/10.1002/047084289X.rb155
  11. https://www.nobelprize.org/prizes/chemistry/2001/noyori/biographical/
  12. https://www.pnas.org/doi/10.1073/pnas.0307928100
  13. https://www.nobelprize.org/prizes/chemistry/2001/summary/
  14. https://pubs.acs.org/doi/10.1021/jo00355a012
  15. https://www.thieme-connect.com/products/ejournals/pdf/10.1055/s-2001-14625.pdf
  16. https://www.sciencedirect.com/science/article/pii/S2666554920300259
  17. https://www.sciencedirect.com/science/article/abs/pii/S0040402003016922
  18. https://orgsyn.org/demo.aspx?prep=v91p0001
  19. https://www.orgsyn.org/Content/pdfs/procedures/v91p0001.pdf
  20. https://www.orgsyn.org/demo.aspx?prep=v91p0001
  21. https://onlinelibrary.wiley.com/doi/10.1002/asia.201301265
  22. https://pubs.acs.org/doi/10.1021/cr020039h
  23. https://link.springer.com/article/10.1023/A:1019121113063
  24. https://www.thieme-connect.com/products/ejournals/html/10.1055/s-2005-869934
  25. https://www.sciencedirect.com/science/article/pii/0926860X95000976
  26. https://pastel.hal.science/pastel-00004596v1/file/Cong_Ma.pdf
  27. https://pubs.acs.org/doi/10.1021/ol047624k
  28. https://www.organic-chemistry.org/synthesis/C1C/arenes/conjugateaddition.shtm
  29. https://pubs.acs.org/doi/10.1021/acs.chemrev.0c00736
  30. https://pubs.rsc.org/en/content/articlelanding/1993/c3/c39930001262
  31. https://pubs.rsc.org/en/content/articlelanding/2000/cc/b001503m
  32. https://onlinelibrary.wiley.com/doi/abs/10.1002/cjoc.20020201102
  33. https://pubs.acs.org/doi/10.1021/jo960426p
  34. https://onlinelibrary.wiley.com/doi/abs/10.1002/1615-4169(20010330)343:3%3C264::AID-ADSC264%3E3.0.CO;2-T
  35. https://pubs.acs.org/doi/10.1021/ar0680015
  36. https://pubs.acs.org/doi/10.1021/ar990080f
Add your contribution
Related Hubs
User Avatar
No comments yet.