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1,1′-Bi-2-naphthol
1,1′-Bi-2-naphthol
1,1′-Bi-2-naphthol
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1,1′-Bi-2-naphthol
Skeletal formula of R-BINOL
Skeletal formula of R-BINOL
Skeletal formula of S-BINOL
Skeletal formula of S-BINOL
Ball-and-stick model of R-BINOL
Ball-and-stick model of R-BINOL
(R)-(+)-BINOL
Ball-and-stick model of S-BINOL
Ball-and-stick model of S-BINOL
(S)-(−)-BINOL
Names
Preferred IUPAC name
[1,1′-Binaphthalene]-2,2′-diol
Other names
  • 1,1′-Bi-2-naphthol
  • 1,1-Binaphthol
  • BINOL
  • Binol
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.009.104 Edit this at Wikidata
UNII
  • InChI=1S/C20H14O2/c21-17-11-9-13-5-1-3-7-15(13)19(17)20-16-8-4-2-6-14(16)10-12-18(20)22/h1-12,21-22H checkY
    Key: PPTXVXKCQZKFBN-UHFFFAOYSA-N checkY
  • InChI=1/C20H14O2/c21-17-11-9-13-5-1-3-7-15(13)19(17)20-16-8-4-2-6-14(16)10-12-18(20)22/h1-12,21-22H
    Key: PPTXVXKCQZKFBN-UHFFFAOYAX
  • (R/S): C1=CC=C2C(=C1)C=CC(=C2C3=C(C=CC4=CC=CC=C43)O)O
Properties
C20H14O2
Molar mass 286.32 g/mol
Melting point 205 to 211 °C (401 to 412 °F; 478 to 484 K)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

1,1′-Bi-2-naphthol (BINOL) is an organic compound that is often used as a ligand for transition-metal catalysed asymmetric synthesis. BINOL has axial chirality and the two enantiomers can be readily separated and are stable toward racemisation. The specific rotation of the two enantiomers is 35.5° (c = 1 in THF), with the R enantiomer being the dextrorotary one. BINOL is a precursor for another chiral ligand called BINAP. The volumetric mass density of the two enantiomers is 0.62 g cm−3.[citation needed]

Preparation

[edit]

The organic synthesis of BINOL is not a challenge as such but the preparation of the individual enantiomers is.

(S)-BINOL can be prepared directly from an asymmetric oxidative coupling of 2-naphthol with copper(II) chloride. The chiral ligand in this reaction is (S)-(+)-amphetamine.[2]

Racemic BINOL can also be produced using iron(III) chloride as an oxidant. The mechanism involves complexation of iron(III) into the hydroxyl, followed by a radical coupling reaction of the naphthol rings initiated by iron(III) reducing into iron(II).

Optically active BINOL can also be obtained from racemic BINOL by optical resolution. In one method, the alkaloid N-benzylcinchonidinium chloride forms a crystalline inclusion compound. The inclusion compound of the (S)-enantiomer is soluble in acetonitrile but that of the (R)-enantiomer is not.[3] In another method BINOL is esterified with pentanoyl chloride. The enzyme cholesterol esterase hydrolyses the (S)-diester but not the (R)-diester.[3] The (R)-dipentanoate is hydrolysed in a second step with sodium methoxide.[4] The third method employs HPLC with chiral stationary phases.[5]

BINOL derivatives

[edit]
Structure of a chiral phosphoric acid derived from BINOL.[6]

Aside from the starting materials derived directly from the chiral pool, (R)- and (S)-BINOL in high enantiopurity (>99% enantiomeric excess) are two of the most inexpensive sources of chirality for organic synthesis, costing less than US$0.60 per gram when purchased in bulk from chemical suppliers.[7] As a consequence, it serves as an important starting material for other sources of chirality for stereoselective synthesis, both stoichiometric and substoichiometric (catalytic).

Many important chiral ligands are constructed from the binaphthyl scaffold and ultimately derived from BINOL as a starting material, BINAP being one of the most well known and important.

The compound aluminium lithium bis(binaphthoxide) (ALB) is prepared by reaction of BINOL with lithium aluminium hydride.[8] In a different stoichiometric ratio (1:1 BINOL/LiAlH4 instead of 2:1), the chiral reducing agent BINAL (lithium dihydrido(binaphthoxy)aluminate) is produced.[9]

It has been employed in an asymmetric Michael reaction with cyclohexenone and dimethyl malonate:

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

1,1′-Bi-2-naphthol

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1,1'-Bi-2-naphthol, commonly abbreviated as BINOL, is a chiral C2-symmetric with the molecular formula C₂₀H₁₄O₂, featuring two moieties connected via a between their 1-positions. This linkage imparts through steric hindrance to rotation, resulting in stable (R)- and (S)-enantiomers that do not racemize under typical conditions, with an energy barrier of approximately 37.8 kcal/mol. First resolved into its enantiopure forms in 1971 by Jacques and co-workers, BINOL has become a in stereoselective chemistry due to its rigid structure and ability to form complexes with metal ions. BINOL's physical properties include a white to beige powder appearance, a of 215–218 °C, and limited solubility in but good solubility in organic solvents like dioxane (50 mg/mL). It is commercially available in both racemic and enantiopure forms on a large scale, enabling widespread adoption. considerations classify it as toxic by (LDLo 42 mg/kg in mice) and an irritant to and eyes, with incompatibility toward strong oxidizing agents. The compound's significance stems from its versatility as a and in asymmetric , facilitating reactions such as Diels-Alder cycloadditions, Michael additions, and enantioselective alkylations with dialkylzinc reagents. Early applications in host-guest chemistry were pioneered by Cram in the 1970s, evolving into its role in transition metal-catalyzed processes involving , , copper, and other metals, including the BINOL-enabled enantioselective C–H thiolation of ferrocenes, for C-H activation and cross-coupling reactions. Beyond synthesis, BINOL derivatives serve in molecular recognition, chiral sensing, and , including the construction of chiral polymers, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs). Its adoption extends to chiral separations in pharmaceuticals, liquid crystals, and fragrances, underscoring its broad impact across chemical disciplines.

Nomenclature and history

Names and identifiers

1,1'-Bi-2-naphthol is the common name for the organic compound systematically known by the IUPAC name [1,1'-binaphthalene]-2,2'-diol. It is widely abbreviated as BINOL in scientific literature. The compound has the molecular formula C20_{20}H14_{14}O2_{2} and a molecular weight of 286.32 g/mol. Standard chemical identifiers for 1,1'-bi-2-naphthol are summarized in the following table:
Identifier TypeValueNotes
CAS Registry Number (racemic)602-09-5For the racemic mixture.
CAS Registry Number ((R)-(+)-enantiomer)18531-94-7Specific to the (R)-(+)-BINOL.
CAS Registry Number ((S)-(-)-enantiomer)18531-99-2Specific to the (S)-(-)-BINOL.
Canonical SMILESC1=CC=C2C(=C1)C=CC(=C2C3=C(C=CC4=CC=CC=C43)O)ORepresentation of the core structure.

Discovery and development

1,1′-Bi-2-naphthol (BINOL) was first synthesized in 1926 by Karl von Auwers and Otto Hövels as a during oxidative coupling reactions involving derivatives. This initial highlighted its formation through radical-mediated dimerization, though its potential applications remained unexplored at the time. Early work focused on structural rather than , with BINOL noted for its atropisomeric nature due to restricted rotation around the biaryl bond. The chiral properties of BINOL gained recognition in the 1970s amid growing interest in asymmetric synthesis, with biaryl atropisomers explored as viable chiral auxiliaries. The first resolution into enantiopure forms was achieved in 1971 by and co-workers via formation of a cyclic with cinchonine. Its breakthrough came in 1979 when Ryoji Noyori demonstrated BINOL's effectiveness as a chiral in the asymmetric hydrosilylation of aromatic ketones and aldehydes using diphenylsilane in the presence of a complex, achieving notable enantioselectivities. This application spurred further developments in the 1980s, including Noyori's extension to related phosphine ligands like for ruthenium-catalyzed , which earned him the 2001 for chirally catalyzed reactions. BINOL became commercially available during this period from suppliers like , facilitating wider adoption in research. Post-2016 research has emphasized sustainable synthesis methods and novel applications, such as green oxidative cross-coupling in using nanoparticles to produce racemic BINOL in high yields. Studies on photo-racemization in 2016 revealed that UV induces both and of BINOL, informing strategies for controlling its in dynamic systems. Additionally, investigations into metal-coordinated BINOL derivatives demonstrated tunable helical scaffolds, as shown in 2013 studies, with ongoing work in the 2020s, such as the 2025 development of (S)-BINOL-derived chiral picolinate ligands as platforms for new polymer frameworks (New J. Chem., DOI: 10.1039/D5NJ01654A), exploring these for responsive materials and in the 2020s.

Structure and stereochemistry

Molecular structure

1,1′-Bi-2-naphthol (BINOL) is composed of two moieties linked by a biaryl carbon-carbon bond at the 1 and 1′ positions, forming a C20H14O2 framework with along the biaryl axis. The central biaryl C-C bond exhibits a of 1.494 , characteristic of a with restricted rotation due to steric hindrance from the adjacent ortho substituents, imparting partial double bond character that contributes to the molecule's atropisomerism. The two phenolic hydroxyl groups are positioned at the 2 and 2′ carbons, immediately adjacent to the biaryl linkage, with typical O-H bond lengths around 0.96 as found in phenolic systems. In the solid state, the of (R)-BINOL crystallizes in the trigonal P3121, featuring an intramolecular O-H···O between the two hydroxyl groups that closes an S(6) ring and stabilizes the molecular conformation. This ing interaction, with an O···O distance of approximately 2.96 at , orients the OH groups in a synclinal arrangement relative to the biaryl axis, reinforcing the overall rigidity of the structure. The highlights the atropisomeric axis passing through the 1,1′ biaryl bond, with the rings twisted at a of about 90°, preventing free rotation and preserving .

Axial chirality and enantiomers

1,1′-Bi-2-naphthol (BINOL) displays through atropisomerism, a form of resulting from hindered rotation about the central 1,1′ biaryl bond. This restriction stems from the significant steric hindrance imposed by the ortho-positioned hydroxy groups and the bulky ring systems, which prevent free rotation and give rise to non-superimposable mirror-image enantiomers. The high energy barrier to , experimentally determined as 37.8 kcal/mol, ensures that the s are configurationally stable at , enabling their isolation and use in chiral applications. The (R)- exhibits a positive of [+35.5° (c=1, THF)], while the (S)- shows a negative rotation of [-35.5° (c=1, THF)], distinguishing them optically. Racemization of BINOL requires heating to temperatures exceeding 180°C, with significant interconversion observed around 220°C in solution. (DFT) studies from 2004 elucidate the mechanism, revealing that the involves torsion around the inter-ring C–C bond, where the naphthyl rings slip past each other in a concerted manner, overcoming the steric repulsion between ortho substituents. More recent computational analyses in the 2020s corroborate this pathway, emphasizing the role of the hydroxy groups in modulating the barrier through hydrogen bonding effects in the . In synthetic contexts, atropselectivity for BINOL derivatives is achieved by employing chiral auxiliaries or catalysts that bias the rotational preference during bond formation, such as metal complexes or organocatalysts that induce dynamic kinetic resolution.

Physical and chemical properties

Physical characteristics

1,1'-Bi-2-naphthol (BINOL) is a white to off-white crystalline solid. The racemic form has a melting point of 214–217 °C, while the enantiomers melt at slightly lower temperatures of 207–212 °C. BINOL exhibits good solubility in polar organic solvents such as (30 mg/mL), dimethylformamide (35 mg/mL), and (15 mg/mL), but is insoluble in . The of the solid is approximately 1.3 g/cm³. It decomposes before boiling, with an estimated of 389 °C.

Spectroscopic data

The spectroscopic properties of 1,1'-bi-2-naphthol (BINOL) provide essential data for its structural identification and enantiomeric distinction. (NMR) spectroscopy reveals characteristic signals in the 1H NMR spectrum recorded in CDCl₃, where the aromatic protons appear in the range of 7.0–8.0 ppm and the OH protons manifest as a broad singlet at approximately 5.5 ppm due to hydrogen bonding and exchange. The ¹³C NMR spectrum displays 10 signals corresponding to the symmetric aromatic carbons, consistent with the molecule's biaryl framework. Infrared (IR) spectroscopy of BINOL exhibits a strong, broad O-H stretching band at 3400 cm⁻¹ attributable to the phenolic hydroxyl groups, along with C=C stretching vibrations of the aromatic rings in the 1600–1450 cm⁻¹ region. Ultraviolet-visible (UV-Vis) absorption spectroscopy shows maxima at 205 nm and 280 nm, arising from π-π* transitions within the extended naphthyl system. Mass spectrometry confirms the molecular ion peak at m/z 286 ([M]⁺), corresponding to the C₂₀H₁₄O₂, with common fragmentation patterns involving loss of OH (m/z 269). (CD) spectra differentiate the enantiomers, with (R)-BINOL displaying a positive at 230 nm due to the influencing excitonic coupling in the naphthyl chromophores.

Synthesis

Racemic preparation

The racemic mixture of 1,1′-bi-2-naphthol (BINOL) is most commonly prepared via oxidative coupling of 2-naphthol using iron(III) chloride (FeCl₃) as the oxidant in 1,2-dichloroethane. This classic method, originally developed by Dianin in 1873 and refined in subsequent procedures, proceeds through a radical mechanism involving one-electron oxidation of 2-naphthol to a naphthoxy radical, followed by C1–C1' dimerization to form the biaryl bond. Typical conditions involve treating 2-naphthol (1 equiv) with FeCl₃ (2–4 equiv) at room temperature to reflux for 1–2 hours, yielding rac-BINOL in 80–90% isolated yield after workup. Alternative oxidants, such as copper(II) chloride (CuCl₂) or vanadium oxytrifluoride (VOF₃), offer viable substitutes for FeCl₃, often with similar radical-based mechanisms but varying solvent compatibility and reaction times of 1–24 hours at room temperature to reflux. For instance, CuCl₂ (1–2 equiv) in methanol or tetrahydrofuran provides rac-BINOL in up to 93% yield, while VOF₃ enables efficient coupling under anhydrous conditions. These methods maintain high efficiency for bulk production without inducing enantioselectivity. The crude product is typically purified by recrystallization from , yielding analytically pure rac-BINOL, or by if necessary for removal of polar byproducts.

Enantioselective synthesis and resolution

One prominent method for the of 1,1′-bi-2-naphthol (BINOL) involves the oxidative homocoupling of mediated by CuCl₂ in the presence of a chiral ligand, such as (S)-(+)-. Developed in the late , this approach functions as a dynamic kinetic resolution, where the chiral coordinates to the , facilitating selective formation of the (S)- with up to 96% enantiomeric excess (ee) and 98% yield under mild conditions in . The method's efficiency stems from the rapid of the intermediate BINOL under the reaction conditions, allowing continuous enantioselective capture. Enzymatic resolution provides a biocatalytic route to enantiopure BINOL from the racemic diacetate precursor, leveraging the of for . from cepacia (also known as cepacia lipase, PS-C I-30) catalyzes the selective deacetylation of the (R)-diacetate in a biphasic organic-aqueous system, yielding (R)-BINOL with >99% at approximately 50% conversion, while the unreacted (S)-diacetate can be hydrolyzed chemically to recover the . This kinetic resolution is scalable and operates under ambient conditions, with the enzyme's preference for the (R)- attributed to differential binding in the . Similar high enantioselectivities have been achieved with related sp. lipases in buffer-THF mixtures. Classical resolution of racemic BINOL exploits diastereomeric salt formation with chiral resolving agents, followed by fractional . Treatment of racemic BINOL with N-benzylcinchonidinium chloride in forms a 1:1 complex with the (S)-, which crystallizes selectively with >99% and 45% recovery; the (R)- is obtained from the mother liquor after regeneration and recycling of the agent. This inclusion-based method is practical for large-scale production due to the agent's recyclability (up to 95% recovery) and avoids harsh conditions, with the mechanism involving host-guest complexation driven by hydrogen bonding and π-stacking interactions. Chiral chromatographic separation offers a versatile, non-destructive approach for both analytical and preparative isolation of BINOL enantiomers using polysaccharide-based stationary phases. Normal-phase HPLC with Chiralpak AD or OD columns (derived from tris(3,5-dimethylphenylcarbamate)) resolves racemic BINOL with baseline separation (Rs > 1.5) using hexane-isopropanol mobile phases, enabling isolation of enantiopure forms at gram scales with >99% ee. Preparative applications often employ stacked columns or simulated moving bed technology for higher throughput, making this method ideal for purity verification and small-batch purification in research settings. Recent advances in enantioselective BINOL synthesis include biocatalytic methods for construction, such as enzyme-mediated approaches achieving high for biaryl compounds including BINOL derivatives as of 2025.

Applications

Role in asymmetric

1,1'-Bi-2-naphthol (BINOL) serves as a foundational chiral in asymmetric catalysis, leveraging its to induce enantioselectivity in various metal-mediated reactions. Its rigid biaryl structure forms stable chelates with metal centers, creating a chiral pocket that differentiates between enantiotopic faces of prochiral substrates. This role has been pivotal in developing efficient synthetic routes to enantiopure compounds, particularly in Lewis acid-catalyzed transformations. BINOL readily forms complexes with metals such as Ti(IV), Zr(IV), and rare earth elements like La(III) or Yb(III), enabling for enantioselective processes. For instance, the BINOL-Ti(IV) complex, often prepared from BINOL and Ti(OiPr)₄, acts as an effective catalyst in asymmetric Diels-Alder reactions, achieving enantiomeric excesses (ee) up to 99% for cycloadducts from acrylates and . Similarly, BINOL-rare earth metal complexes, such as those with La or Sm, promote aldol additions and epoxidations by coordinating to carbonyl groups, with reported ee values exceeding 95% in the Henry reaction (nitroaldol) of aldehydes with . These complexes highlight BINOL's versatility in modulating metal Lewis acidity while enforcing stereocontrol through its atropisomeric framework. In hydrogenation chemistry, BINOL serves as the chiral precursor for BINAP, a diphosphine central to Noyori's ruthenium-catalyzed of ketones and functionalized alkenes, which routinely delivers products with >99% and has broad industrial applications in pharmaceutical synthesis. For Michael additions, BINOL-derived phosphoric acids function as Brønsted acid catalysts, facilitating 1,4-additions of nucleophiles to α,β-unsaturated carbonyls with enantioselectivities often >95% , as seen in the addition of indoles to chalcones. The phosphate's orients the substrate via hydrogen bonding, enhancing facial selectivity. Recent advancements include BINOL's involvement in C-H activation; for example, a Ni(II)-BINOL complex catalyzes enantioselective C-H of 1,3-dienes via desymmetrization, achieving up to 96% ee (as of 2024). As of 2025, BINOLates have emerged as potent reducing photocatalysts for activating inert bonds and reducing unsaturated bonds under visible light. Mechanistically, BINOL's imposes a helical arrangement around the metal, generating a dissymmetric environment that biases substrate approach and product enantioselection, as elucidated in studies of Ti and rare earth complexes. This principle underpins BINOL's enduring impact in asymmetric synthesis.

Uses in materials and other fields

BINOL has been incorporated into chiral stationary phases (CSPs) for (HPLC) to enable the enantiomeric separation of various compounds. By immobilizing enantiopure BINOL derivatives onto supports, these CSPs facilitate direct resolution of racemic mixtures through interactions such as hydrogen bonding and π-π stacking between the and the chiral selector. For instance, (R)-BINOL linked to silica has been employed as a CSP for analyzing chiral s, demonstrating effective enantioseparation in normal-phase HPLC conditions. Similarly, mesoporous silica modified with BINOL-based chiral diol hosts has shown utility in separating racemic and pharmaceuticals like 2,2'-dihydroxy-1,1'-dinaphthyl, with selectivity arising from the host-guest complexation at the chiral sites. More recent developments include BINOL-derived polyimine s bonded to silica, which provide enhanced chiral recognition for diverse enantiomers due to the rigid, C2-symmetric framework of the (as of 2024). In , BINOL (meth) derivatives serve as monomers for synthesizing high-refractive-index polymers suitable for optical films and lenses. These derivatives, featuring the rigid, aromatic BINOL core, yield photocurable compositions with refractive indices exceeding 1.65, attributed to the high density of π-electrons and minimal free volume in the polymer network. A 2010 describes the preparation of such 1,1'-bi-2-naphthol (meth)s via esterification of BINOL hydroxyl groups, enabling UV-curable polymers for applications in antireflective coatings and waveguides. Ongoing research continues to explore these materials for advanced photonic devices, leveraging their thermal stability and optical transparency. As of July 2025, BINOL has been incorporated into (II) complexes exhibiting circularly polarized (CPL), enhancing applications in chiroptical materials for displays and sensors. Photo-responsive materials based on BINOL exhibit dynamic changes under light irradiation, paving the way for applications in chiral liquid crystals and smart polymers. Studies on the photo-racemization of (R)-BINOL under UV light reveal a mechanism involving torsional rotation around the biaryl bond, leading to partial or complete loss of optical activity, which can be controlled for reversible switching. In , investigations into photo-racemization coupled with demonstrated that irradiated BINOL derivatives form chiral polymers with tunable helical structures, suitable for liquid crystalline phases that respond to light stimuli. These properties have been exploited to develop photochromic liquid crystals, where BINOL's induces supramolecular organization, enabling applications in optical and displays. BINOL-based fluorescent probes are widely used as sensors for metal ions, operating via chelation-enhanced (CHEQ) mechanisms. The dihydroxyl groups of BINOL coordinate with metal cations, such as Cu²⁺, inducing fluorescence through (PET) or intramolecular charge transfer (ICT) pathways. A BINOL derivative functionalized with an linker has been reported to selectively detect Cu²⁺ in aqueous media with a of 10⁻⁷ M, showing a significant fluorescence turn-off response due to CHEQ. These probes extend to other ions like Zn²⁺ and Fe³⁺, where binding alters the excited-state dynamics, providing high selectivity over competing metals. BINOL-derived probes serve in biomedical applications for chirality sensing, such as detecting enantiomers of like in aqueous environments via fluorescent responses. These probes leverage BINOL's inherent to differentiate - and D-forms through diastereomeric complexation, aiding in studies of chiral biomolecules (as of 2024).

Derivatives

Phosphine-based derivatives

One of the most significant phosphine-based derivatives of 1,1′-bi-2-naphthol (BINOL) is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (), in which the hydroxyl groups at the 2 and 2′ positions are replaced by diphenylphosphino groups. This substitution maintains the inherent to the binaphthyl core due to restricted rotation about the 1,1′ biaryl bond. BINAP is typically synthesized from enantiopure BINOL through directed ortho-lithiation using (n-BuLi) in the presence of (TMEDA) to generate the dilithiated intermediate, followed by reaction with chlorodiphenylphosphine to yield the bis(); subsequent reduction with affords the diphosphine in 70–80% overall yield. This ligand has been commercially available since the , facilitating its widespread adoption in synthetic applications. In asymmetric catalysis, excels as a bidentate for transition metals, particularly in complexes (Ru-BINAP) that catalyze the enantioselective of prochiral alkenes and ketones, often delivering enantiomeric excesses greater than 99%. For instance, Ru-BINAP enables the industrial-scale production of (R)-1,2-propanediol, a key intermediate in synthesis, with near-perfect stereocontrol. Palladium-BINAP systems similarly promote asymmetric cross-coupling reactions, including allylic aminations and couplings with amines, achieving high enantioselectivities in carbon-nitrogen bond formation. The impact of on chiral catalysis was recognized in the 2001 , awarded to Ryoji Noyori for pioneering chirally catalyzed reactions using such ligands. Variants of BINAP, such as those with modified phosphino substituents (e.g., Tol-BINAP), and related ligands like SEGPHOS, feature tunable bite angles that optimize performance for specific substrates in hydrogenations and conjugate additions by adjusting the P-M-P coordination geometry.

Other modified BINOL compounds

Aluminum lithium bis(binaphoxide) (ALB), a heterobimetallic complex formed from BINOL and aluminum , serves as a catalyst for the enantioselective reduction of aromatic ketones to chiral secondary alcohols, achieving enantiomeric excesses up to 90% with optimized BINOL derivatives like H8-BINOL. This reagent enhances selectivity through of the aluminum center by the binaphthoxide ligands, facilitating delivery in asymmetric fashion. BINAL-H, a binaphthyl-modified aluminum hydride reagent derived from BINOL, lithium aluminum hydride, and an alcohol, functions as a stoichiometric for the enantioselective conversion of prochiral ketones and imines to alcohols and amines, respectively, with high stereocontrol particularly for substrates bearing π-systems. Its mechanism involves a chiral environment around the aluminum species, enabling kinetic resolution in of α-chloro ketones and imines. Bridged BINOL derivatives enhance solubility and tunability for catalytic and optical applications; for instance, polyethylene glycol (PEG)-supported variants, such as PEG-BINOL, enable recyclable homogeneous catalysis in reactions like asymmetric Michael additions with calcium ions, maintaining enantioselectivity while allowing easy separation via precipitation. Similarly, methylene-bridged BINOL scaffolds with phenylethynyl (PE) substituents (3-PE to 8-PE series) exhibit extended π-conjugation, leading to red-shifted absorption (up to 369 nm for 4-PE) and high fluorescence quantum yields (77-81% for select members), as revealed in a 2024 study on their chiroptical properties including circularly polarized luminescence. These PE-bridged compounds are synthesized via selective halogenation followed by Sonogashira coupling, locking the binaphthyl atropisomer for stable helical conformations. Functionalization at the 6,6'-positions, such as in 6,6'-dibromo-BINOL, provides precursors for cross-coupling reactions; of the hydroxyl groups followed by with silylethynyl units yields dynamic scaffolds that toggle between and single-turn helical conformations upon metal coordination, as demonstrated in (II) complexes for potential stimuli-responsive materials. , prepared by esterification of the 2,2'-hydroxyl groups with , form polymers with refractive indices exceeding 1.65, suitable for low-dispersion optical components like lenses, as outlined in a 2010 emphasizing their transparency and thermal stability. Common synthetic routes to these modified BINOLs involve esterification of the phenolic OH groups using acid chlorides or anhydrides (e.g., for monopivalate protection) to direct , followed by deprotection via . at 3,3'-positions proceeds via ortho-lithiation with n-BuLi/TMEDA and electrophilic quenching with Br2 or I2, yielding 3,3'-dibromo-BINOL in 72% yield, while 6,6'-dibromination occurs directly with Br2 in CH2Cl2 at low temperature, affording the product in 99% yield after OH protection if needed.

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