Binaphthyl Derivatives Research Articles

ChemInform Abstract: Synthetic Approaches to Axially Chiral C2-Symmetric Nonracemic Binaphthyl Derivatives

ChemInform Abstract: Synthetic Approaches to Axially Chiral C2-Symmetric Nonracemic Binaphthyl Derivatives

ChemInform Abstract: New Chiral Binaphthyl Building Blocks: Synthesis of the First Optically Active Tetrathiafulvalene Dimers.

New enantiomerically pure binaphthyl derivatives bearing triphenylphosphine or phosphonate groups have been synthesized and used as building blocks to prepare the first optically active tetrathiafulvalene dimers.

Synthesis and antibacterial studies of binaphthyl-based tripeptoids. Part 2

A compact synthesis of 15 new binaphthyl-based dicationic tripeptoids and one biphenyl based dicationic tripeptoid is described. Fourteen of these tripeptoids resulted from variation of the C-2′ ether substituent of the binaphthyl unit. An O- iso-butyl ether binaphthyl derivative was found to be the most active against Staphylococcus aureus (MIC 1.95 μg/mL). The biphenyl analogue also showed good activity against S. aureus (MIC 1.95 μg/mL). These compounds, however, were less active against four vancomycin-resistant strains of enterococci (VRE) than some of our previously developed compounds that had an O- iso-pentyl ether substituent on the binaphthyl unit and a C-2 l-Leu moiety.

Comparison of HPLC enantioseparation of substituted binaphthyls on CD‐, polysaccharide‐ and synthetic polymer‐based chiral stationary phases

Retention and enantioseparation behavior of ten 2,2'-disubstituted or 2,3,2'-trisubstituted 1,1'-binaphthyls and 8,3'-disubstituted 1,2'-binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on beta-CD, polysaccharides (tris(3,5-dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans-1,2-diamino-cyclohexane, trans-1,2-diphenylethylenediamine and trans-9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid CSPs). Normal-, reversed-phase and polar-organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non-identical groups and a chiral axis in the 1,2' position had the greatest impact on the enantiomeric discrimination. The 8,3'-disubstituted 1,2'-binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose-based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system.

Twisting Power of a Novel Binaphthyl Derivative Possessing Laterally Attached Mesogenic Units

We prepared a novel binaphthyl derivative possessing laterally attached mesogenic units, (R)-2, 2′-bis{6-[2-(4-octyloxyphenyloxycarbonyloxy)-5-octyloxyphenyloxycarbonyl]hexyloxy}-1,1′-binaphthyl [( R )- 1 ], and that possessing terminally attached mesogenic units, (R)-2, 2′-bis{6-[4-(4-octyloxyphenyloxycarbonyl)phenyloxycarbonyl]hexyloxy}-1, 1′-binaphthyl [( R )- 2 ]. We investigated their induced helical senses and pitches in the chiral nematic (N*) and chiral smectic C (SmC*) phases in the mixture with a host liquid crystal. ( R )- 1 induced a left-handed (LH) helix in the N* phase, whereas ( R )- 2 induced a right-handed (RH) helix. We discuss chirality transfer from each binaphthyl derivative to a host liquid crystal.

A Vibrational Raman Optical Activity Study of 1,1′‐Binaphthyl Derivatives

The Raman polarized and vibrational Raman optical activity (VROA) backward spectra are simulated for a series of 2,2'-substituted 1,1'-binaphthyl compounds presenting a variety of torsion angles between the two naphthalene rings. The substitution prevents free rotation along this torsion angle and the chirality of these compounds is thus called atropisomerism. However, the rotation is not completely frozen so that two different conformations, namely cisoid and transoid, are found and their Raman and VROA signatures are studied. As expected, the Raman spectra are not very sensitive whereas the VROA spectra present more complex patterns, which evolve as a function of the torsion angle between the two naphthalene groups. In particular, our analysis shows that some modes can be used as a probe for the determination of the torsion angle of these molecules in solution. The contributions of both invariants to the VROA backward intensity are also assessed.

Chiral binaphthyl receptors bearing imidazolium or urea groups for the recognition of anions

Two new binaphthyl derivatives 1 and 2 bearing two imidazolium, or bisurea groups were investigated as fluorescent chemosensors for the chiral anion recognition. Receptors 1 and 2 displayed a better selectivity for (S)-2-phenylbutylate over (R)-2-phenylbutylate. Isothermal titration calorimeter methods, fluorescence as well as theoretical calculations are utilized to explain chiral selectivity.

Palladium complexes with abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazolium ions and their application in Suzuki coupling

Chiral and achiral pincer type palladium complexes bearing abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazole are reported. Both complexes are effective as catalysts for non-asymmetric Suzuki coupling reaction for the synthesis of biphenyl derivatives. However, both the complexes failed to catalyze the formation of binaphthyl derivatives, by the asymmetric Suzuki coupling in case of the chiral complex and the non-asymmetric version in case of the achiral pincer complex. Instead deboronation of arylboronic acid occurred very efficiently leaving the aryl bromide intact.

Synthesis of Carbocyclic Aromatic Compounds Using Ruthenium-Catalyzed Ring-Closing Enyne Metathesis

General synthetic methods of substituted carbocyclic aromatic compounds are reported. Ring-closing enyne metathesis (RCEM)/dehydration of 1,5-octadien-7-yn-4-ols 6 and RCEM/tautomerization of 1,5-octadien-7-yn-4-ones 7 furnished a wide variety of substituted styrenes 4 and 4-vinylphenols 8, respectively. Acyclic precursors 6 and 7 were readily prepared from beta-halo-alpha,beta-unsaturated aldehydes 9 or 3-halo-2-propene-1-ols 13 by utilizing combinations of the Sonogashira coupling, allylation, and the Dess-Martin oxidation. The RCEM/dehydration for the synthesis of 1,3,5-tris(1-phenylethenyl)benzene derivative 4r and the RCEM/RCM/dehydration for the synthesis of 1,1'-binaphthyl derivative 19a are also presented as applications of this method.

A new route to 2,2′,3,3′-tetrasubstituted binaphthyls

Based on an ortho-lithiation protocol of 2,2′-dibromo-1,1′-binaphthyl four tetrasubstituted binaphthyls, 2,2′-dibromo-3,3′-diiodo-, 3,3′-dibromo-2,2′-diiodo-, 2,2′,3,3′-tetrabromo-, and 2,2′,3,3′-tetraiodo-1,1′-binaphthyls have been prepared in excellent yield which in turn proved to be versatile key intermediates in the synthesis of various 2,2′,3,3′-tetrasubstituted 1,1′-binaphthyl derivatives.

A binaphthyl derivative with a wide temperature range of a blue phase

We prepared a binaphthyl derivative possessing two 2,3-difluoro-1,4-diphenylbenzene units, and then investigated the phase transition behaviour. On cooling, the compound was found to exhibit a phase sequence of iso liq–blue phase–smectic phase. The temperature of the blue phase with a cubic structure was about 30 K. An electric-field-induced phase transition was observed in the blue phase. On heating, the compound exhibited marked phase separation. Some regions showed a phase sequence of cryst–chiral nematic (N*)–blue phase (BP)–iso liq, whereas others showed that of cryst–iso liq. The temperature range of coexisting crystal and iso liq phases was about 29 K. The phase separation is quite unusual for a single compound. The phase-transition behaviour is discussed in terms of the molecular shape of the binaphthyl derivative.

Multivariate approach for the enantioselective analysis in micellar electrokinetic chromatography-mass spectrometry: I. Simultaneous optimization of binaphthyl derivatives in negative ion mode

A mixture of two molecular micelles polysodium N-undecenoxy carbonyl- l-leucinate, (poly- l-SUCL) and polysodium N-undecanoyl leucylvalinate, (poly- l-SULV) was utilized in micellar electrokinetic chromatography-electrospray ionization-mass spectrometry (MEKC-ESI-MS) to simultaneously separate and detect enantiomers of binaphthyl derivatives. Separation parameters such as background buffer composition, voltage, temperature, and nebulizer pressure were optimized using a multivariate central composite design (CCD). Baseline enantioseparation for both analytes was achieved. The CCD was also used in the optimization of sheath liquid and spray chamber parameters to achieve optimum ESI-MS response. The results demonstrate that CCD is a powerful tool for the optimization of MEKC-MS parameters and the response surface model analysis can provide in-depth statistical understandings of the significant factors required to achieve maximum enantioresolution and ESI-MS sensitivity.

Molecular design for stabilizing a blue phase III and electro‐optical switching in the blue phase

Abstract— The molecular design of a liquid crystal to stabilize a blue phase III (BPIII) is reviewed, and the electro‐optical switching with a response time on the order of 10−2 sec for BPIII exhibited by a novel chiral liquid crystal is reported. Binaphthyl derivatives and T‐shaped compounds are presented, and the structure‐property correlations of the chiral compounds are discussed. Two origins of the twisting power of the compounds, i.e., their inherent molecular chirality and the chirality‐induced twist conformation, play an important role in the appearance of the BPIII. Furthermore, BPIII was also induced in some binary mixtures of a host nematic liquid‐crystal possessing molecular biaxiality and a conventional chiral compound. The electro‐optical switching in the BPIII is attributed to an electric‐field‐induced phase transition between the BPIII and nematic (N) phases. BPIII is on the microscopically twisted nematic order, but is macroscopically isotropic. Therefore, the present technology can offer a pronounced black state in the BPIII without surface treatment and a homogeneous bright state in the induced N phase.

Fluorescent sensors for Ca 2+ and Pb 2+ based on binaphthyl derivatives

Two novel binaphthyl compounds have been synthesized for the selective fluorescent recognition of Ca 2+ or Pb 2+. By introducing different terminal groups to the receptor unit, the fluorescence signals of the receptors are significantly changed: 1 is fluorescence enhancement for Ca 2+, 2 is fluorescence quenching for Pb 2+. The binding properties for metal ions were examined by the absorption and fluorescence spectra. The fluorescence intensity enhancement was ascribed to the complex formation between Ca 2+ and 1 which blocked the photo-induced electron transfer process.

Ti-Catalyzed Allylation of Aldehydes Promoted by Silica-Supported BINOL

A mesoporous silica-supported BINOL ligand (SBA-15/BINOL) was prepared by anchoring binaphthyl derivative 1 onto SBA-15 using Cl(CH2)3Si(OEt)3 (2) as a tethering agent, followed by TMS-capping and O-MOM cleavage. SBA-15/BINOL promoted the titanium-catalyzed alkylation of aromatic aldehydes with tetraallyltin under microwave conditions to give the corresponding homoallylic alcohols in 85.1-99% conversion with 92.5-99.9% selectivity.

A hybrid‐type, chiral π‐conjugated polymer wrapped with polyhedral oligomeric silsesquioxanes

AbstractA novel hybrid‐type chiral binaphthyl‐based polyarylene derivative with polyhedral oligomeric silsesquioxanes (POSS) units 2a was prepared by Suzuki–Miyaura coupling polymerization from a chiral (R)‐6,6′‐dibromo‐2,2′‐diPOSS‐substituted 1,1′‐binaphthyl derivative 1a and p‐biphenylene diboronic acid. As a reference, a binaphthyl‐based polyarylene derivative without POSS unit 2b was also prepared. The obtained polymers were studied with thermogravimetric analysis, optical rotations, circular dichroism (CD), ultraviolet‐visible, and photoluminescence (PL) spectra. Gel permeation chromatography measurements of 2a and 2b showed that their number‐average molecular weights were 13,300 and 16,500, respectively. The thermal stability of POSS‐modified polymer 2a (temperature of 10% weight loss; T10 = 380 °C) was extremely high compared with that of polymer without POSS unit 2b (T10 = 335 °C) due to the siliceous bulky POSS segments on the side chains. The specific optical rotation [α]D was −66.7° (c 0.06, CHCl3) for 2a and −62.3° (c 0.06, CHCl3) for 2b. The CD spectra showed that these two polymers had very similar and strong Cotton effects. Film polymer 2a showed almost the same PL spectrum as that in dilute CHCl3 solution, indicating that bulky POSS units strongly suppressed intermolecular aggregation of the π‐conjugated polymer backbone. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6035–6040, 2008

Powerful helicity inducers: axially chiral binaphthyl derivatives

Axially chiral binaphthyl derivatives with highly twisting powers were synthesised by substituting phenylcyclohexyl (PCH) mesogenic moieties into 2,2′ positions or 2,2′,6,6′ positions of binaphthyl rings. The di‐ and tetra‐substituted binaphthyl derivatives were adopted as chiral dopants to induce chiral nematic liquid crystals (N*‐LCs). The helical twisting power (βM) of tetra‐substituted binaphthyl derivative, D‐3, having direct linkages between the PCH moieties and the binaphthyl rings at the 6,6′ positions, was 449 µm−1. This is ca. 2.6 times larger than that (171 µm−1) of di‐substituted one, D‐1. For systematic investigation of helical twisting power in the binaphthyl derivatives, several tetra‐substituted binaphthyl derivatives (D‐2–D‐9) were synthesised by introducing different aromatic moieties into the 6,6′ positions of the binaphthyl rings without methylene spacer. When the substituents group changed from p‐hexaoxyphenyl to p‐hexaoxybiphenyl, the helical twisting powers of the binaphthyl derivatives increased from 234 to 757 µm−1. Interestingly, D‐3 and D‐9 exhibited liquid crystallinity. Although the liquid crystallinity of the chiral dopant has no direct influence on the helical twisting power of the N*‐LC, it plays a role in increasing the miscibility of the chiral dopant to host N‐LC, leading to a raise of the upper limit in concentration of the chiral dopant. Consequently, both the high helical twisting power and the high miscibility of D‐3 allowed us to prepare a highly twisted N*‐LC, the helical pitch of which is in the nano‐order, e.g. 270 nm.

Helical Structure Induced by a Binaphthyl Derivative Possessing Two Biphenyl Moieties

We prepared (R)-2, 2′-bis{6-[4-(4-(octyloxycarbonyl)phenyl)phenyloxycarbonyl] hexyloxy}-1, 1′-binaphthyl [(R) -Bi-I(8) ] and the monobiphenyl derivative [(R) -M-I(8) ], and investigated their induced helical senses and pitches in different nematic liquid crystals. With respect to each mixture with 5-heptyl-2-(4-hexyloxypheyl)primidine, a right-handed helix was induced in the mixture with (R)-Bi-I(8) , whereas a left-handed helix was observed in the mixture with (R){-M-I(8)}. On the other hand, a left-handed helix was induced in each mixture with 4-methyloxyphenyl 4-penthlcyclohexane. Furthermore, we investigated the effects of axial chirality and terminal chain length on the twisting power of the binaphthyl derivatives.

Enantioselective Olefin Epoxidation using Axially Chiral Biaryl Azepinium Salts as Catalysts. Rapid in‐situ Screening and Origin of the Stereocontrol

AbstractTo unravel the origin of the stereocontrol in epoxidation reactions of unfunctionalized alkenes by diastereomeric biaryl oxaziridinium salts, two series of novel iminium cations were prepared. These moieties combine (Ra)‐dimethylbiphenyl or (Ra)‐5,5′,6,6′,7,7′,8,8′‐octahydrobinaphthyl cores with chiral exocyclic appendages derived from commercially available (S)‐ or (R)‐3,3‐dimethylbutan‐2‐amine and (S)‐ or (R)‐1‐phenylpropan‐1‐amine. Under biphasic enantioselective olefin epoxidation conditions, in‐situ generated bromide salts of these derivatives have displayed similar or better asymmetric efficiency than the classical binaphthyl derivatives. A structural analysis was performed in search of a correlation between the origin of the stereocontrol/level of enantioselectivity in the products, and dihedral angles around the biaryl twist of the catalysts.

Enantiomeric separations of binaphthyl derivatives by capillary electrophoresis using N‐(2‐hydroxydodecyl)‐L‐threonine as chiral selector: Effect of organic additives

The chiral selectivity of a novel amphiphile, N-(2-hydroxydodecyl)-L-threonine (2-HDT), was evaluated for enantiomeric resolution of three binaphthyl derivatives (+/-)-1,1'-bi-2-naphthol, (+/-)-1,1'-binaphthyl-2,2'-diamine, and (+/-)-1,1'-binaphthyl-2,2'-diylhdrogen phosphate (BNP) by micellar EKC. The effects of three organic modifiers, methanol, isopropanol, and acetonitrile, on the separations of enantiomers of these compounds were investigated. Separation of enantiomers could be achieved in relatively dilute solutions of the pure surfactant. However, best separations of enantiomers were obtained only in the presence of 10% v/v acetonitrile. Enantiomeric impurity in nonracemic mixtures of R- and S-forms of BNP was determined.