Chiral Resolution of l,l'-Binaphthalene-2, 2'-Diol and its (-)-Menthyl Chloroformate derivatives by HPLC with Urea Derivative as Chiral Stationary Phase

Optically pure l,1'-binaphthalene-2,2'-diols are very useful compounds for various application^[1] such as catalyst ligands for asymmetric synthesis, the starting materials for other chiral binaphthyl catalysts and resolving agents for racemic compounds. Consequently, the preparation of optically pure l,l'-binaphthalene-2,2'-diols are of current interest Recently, new methods of resolution of racemic l,1'-binaphthalene-2,2'-diols utilizing (-)-(lR)-menthyl chloroformate as the derivatization agent have been developed^[2,3]. To determine the optical purity of these 1,1'-binaphthalenes, it is necessary to develop a convenient and reliable method for the detection of each stereoisomers.     

A novel chiral mesoporous binaphthyl-silicas: Preparation, characterization, and application in HPLC

Mesoporous organosilicas with both R-(+)-1,1'-binaphthyl-2,2'-diamine and ethane moieties bridging in the framework were synthesized. This mesoporous material was prepared via the one-step co-condensation of N,N'-bis-[(triethoxysilyl)propyl]-(R)-bis-(ureido)-binaphthyl (Si-DABN) with 1,2-bis(triethoxysilyl)ethane (BTSE) using octadecyltrimethylammonium chloride (C(18) TMACl) as a structural directing agent with the aid of a co-solvent (ethanol) in basic medium. The morphology of these bifunctionalized mesoporous organosilicas is sensitive to the Si-DABN mole fraction and the base concentration. And the mesostructure becomes less ordered as the mole fraction of Si-DABN in the initial mixture increases from 10 to 40%. Elemental analysis and Fourier transform infrared (FT-IR) spectrometer indicate that the binaphthyl diamine was successfully introduced to the mesoporous organosilicas. Acidic conditions are more suitable than basic ones for the hydrolysis and condensation of (R)-2,2'-dicyanomethoxy-6,6'-di[(2-triethoxysilyl)ethenyl]-1,1'-binaphthyl, a chiral silane precursors with a short silane side chain on the binaphthyl group. A column packed with these bifunctionalized mesoporous organosilica spheres exhibits greater selectivity for R/S-1,1'-bi-2,2'-naphthol than one packed with commercial SiO(2) grafted with N,N'-bis-[(triethoxysilyl)propyl]-(R)-bis-(ureido)-binaphthyl. Binaphthol and bromosubstituted binaphthol were fully resolved, but two ether derivatives were only partially enantioseparated and the other three ester derivatives were no fully resolved on the column via co-condensation method.     

Rhodium-catalyzed asymmetric hydroformylation of vinylarenes with novel chiral P,N-ligands derived from 1,2:5,6-di-O-cyclohexylidene-d-mannitol

Several new chiral P,N-ligands were prepared from 1,2:5,6-di-O-cyclohexylidene-d-mannitol, 1,1′-binaphthol, and phenyl isocyanate derivatives. Their Rh(I) complexes were applied as catalyst precursors in the asymmetric hydroformylation of vinylarenes. The steric and electronic properties of the phenylcarbamate substituents and the chiral binaphthyl moiety showed remarkable effects on the enantioselectivity and regioselectivity of the reaction. The matching combination of phenylcarbamate and the binaphthyl moiety of the ligand 1,2:5,6-di-O-cyclohexylidene-3-phenylcarbamate-4-[(S)-1,1′-binaphthyl-2,2′-diyl]phosphite-d-mannitol gave 50% ee and an 89/11 b/n ratio (branch-to-normal ratio). A synergic effect between the chiralities of mannitol and the binaphthol moieties was observed. Hydroformylation of the styrene gave the product in 75% ee when 1,2:5,6-di-O-cyclohexylidene-3,4-bis[(R)-1,1′-binaphthyl-2,2′-diyl]phosphite-d-mannitol was used as the chiral ligand.     

Synthesis, helicity, and chromism of optically active poly(phenylacetylene)s carrying different amino acid moieties and pendant terminal groups

Functional phenylacetylene derivatives containing l-alanine and l-leucine moieties with chiral menthyl and achiral n-octyl terminal groups {HC[triple bond]C-C6H4-p-CONHCH(R)CO2R': R = CH3, R'= (-)-(1R,2S,5R)-menthyl [1(-)]; R = CH2CH(CH2)3, R' = (-)-(1R,2S,5R)-menthyl [2(-)]; R'= CH2CH(CH2)3, R' = (+)-(1S,2R,5S)-menthyl [2(+)]; R'= CH2CH(CH2)3, R' = (CH2)7CH3 (2o)} are synthesized. Polymerizations of the acetylene monomers are effected by organorhodium catalysts, giving corresponding polymers P1(-), P2(-), P2(+), and P2o of high molecular weights (Mw up to 1.2 x 10(6)) in high yields (up to 89%). The polymers are thermally stable (Td >or= 300 degrees C) and soluble in common organic solvents. The polymer structures are characterized by IR, NMR, UV, and CD spectroscopies. Intense CD signals are observed in the visible spectral region, indicating that the polymer chains are taking a helical conformation with an excess of preferred handedness. The backbone conjugation and chain helicity of the polymers can be tuned by changing their molecular structures [(a)chiral pendant groups] and by applying external stimuli (solvent and pH). Addition of trifluoroacetic acid to the polymer solutions decreases their molar ellipticities and enhances their backbone conjugations, inducing a halochromism with a continuous and reversible color change (yellow <==> red).     

Enantioselective synthesis of N,O-psiconucleosides

The first enantioselective synthesis of β-d and β-l N,O-psiconucleosides is reported. The synthetic approach is based on the asymmetric 1,3-dipolar cycloaddition of the C-[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]-N-methyl nitrone with ethyl 2-acetyloxyacrylate followed by Vorbrüggen nucleosidation, and removal of the chiral auxiliary. Stereochemical assignments are supported by a DFT theoretical study of the cycloaddition reaction.     

BINOLAM,a recoverable chiral ligand for bifunctional enantioselective catalysis: the asymmetric synthesis of cyanohydrins

[reaction: see text] A new bifunctional catalytic system based on a monometallic aluminum complex is used for the efficient enantioselective cyanation of aldehydes. The ligand (S)- or (R)-2,2'-bis(diethylaminomethyl)-substituted binaphthol (BINOLAM) used is recovered for recycling. This methodology is used for the synthesis of a precursor of epothilone A.     

Preparation of enantiopure norbornane ligands bearing both (2S,3S)-bis(phosphinomethyl) and 7-syn-oxygen functional groups and an application to rhodium-catalyzed asymmetric hydrogenation

Enantiopure bicyclo[2.2.1]heptane derivatives having both (2S,3S)-bis[(diphenylphosphino)methyl] and 7-syn-oxygen functional groups were synthesized by using diastereoselective Diels-Alder reaction of di-(1R)-menthyl fumarate and 5-trimethylsilylcyclopentadiene followed by silver-promoted stereospecific frame rearrangement of a bromolactone intermediate. Rhodium-catalyzed asymmetric hydrogenations were carried out using the diphosphines as a chiral ligand.     

Synthesis of ansa-2,2′-bis[(4,7-dimethyl-inden-1-yl)methyl]-1,1′-binaphthyl and nsa-2,2′-bis[(4,5,6,7-tetrahydroinden1-yl)methyl]-1,1′-binaphthyltitanium and -zirconium dichlorides

2,2′-Bis[(4,7-dimethyl-inden-1-yl)methyl]-1,1′-binaphthyl and [2,2′-bis[(4,5,6,7-tetrahydroinden-1-yl)methyl]-1,1′-binaphthyl]titanium and -zirconium dichlorides have been synthesized from 2,2′-bis(bromomethyl)-1,1′-binaphthylene. 2,2′-Bis(bromomethyl)-1,1′-binaphthylene was alkylated with the lithium salt of 4,7-dimethylindene to yield 2,2′-bis[1-(4,7-dimethyl-indenylmethyl)]-1,1′-binaphthylene (S)-(−)-9. The lithium salt of 9 was metalated with either titanium trichloride followed by oxidation or zirconium tetrachloride to give titanocene dichloride (S)-(+)-10 and zirconocene dichloride 11. The known complexes ansa-[2,2′-bis[(1-indenyl)methyl]-1,1′-binaphthyl]titanium and -zirconium dichlorides were formed and hydrogenated to ansa-[2,2′-bis[(4,5,6,7-tetrahydroinden-1-yl)methyl]-1,1′-binaphthyl]titanium and -zirconium dichlorides 12 and 14 or to ansa-[2,2′-bis[(4,5,6,7-tetrahydroinden-1-yl)methyl]-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl]titanium dichloride 13 whose solid state structure was determined by X-ray crystallography. Complex 13 adopts a C₁-symmetrical conformation in the solid state, but is conformationally mobile in solution, exhibiting C₂-symmetry in its room temperature NMR spectra.     

Atropisomeric (R,R)-2,2'-Bi([2]paracyclo[2](5,8)quinolinophane) and (R,R)-1,1'-Bi([2]paracyclo[2](5,8)isoquinolinophane): synthesis, structural analysis, and chiroptical properties

Atropisomeric (R,R)-2,2'-bi([2]paracyclo[2](5,8)quinolinophane) [(R,R)-1] and (R,R)-1,1'-bi([2]paracyclo[2](5,8)isoquinolinophane) [(R,R)-2] have been prepared in moderate overall yield (17 and 9%, respectively) by a four-step sequence starting from (R)-(-)-4-amino[2.2]paracyclophane and (R)-(-)-4-carboxy[2.2]paracyclophane, respectively. The structures have been determined on the basis of NOE (1)H NMR analysis and molecular mechanics (MM) calculations performed with a Spartan02 program, using the MMF94s force field. A preliminary, qualitative analysis of the chiroptical properties of these two compounds has also been attempted. The main spectral data can be interpreted in terms of an almost planar 2,2'-bisquinoline chromophore inserted in a paracyclophane structure in the case of (R,R)-1, while in the case of (R,R)-2, the main role is played by a distorted 1,1'-bisisoquinoline chromophore. On the basis of the above structural results, a hypothesis about the enantioselection capability of these two molecules has also been formulated.     

A facile synthesis and asymmetric catalytic activity of new 3‐substituted chiral BINOL ligands

Three new chiral ligands, (S)‐3‐(1H‐imidazol‐1‐yl)methyl‐1,1′‐binaphthol [(S)‐ 1 ], (S)‐3‐(1H‐1,2,3‐benzotriazol‐1‐yl)methyl‐1,1′‐binaphthol [(S)‐ 2 ] and (S)‐3‐(2H‐1,2,3‐benzotriazol‐2‐yl)methyl‐1,1′‐binaphthol [(S)‐ 3 ], were prepared by a simple method. They showed moderate catalytic properties for the asymmetric addition of diethylzinc to benzaldehyde in the presence of titanium tetraisopropoxide. Copyright © 2007 John Wiley & Sons, Ltd.     

2,2-Dimethyl-3-[(4-methylphenyl)sulfonyl]-2,3-dihydro-1,3,2-benzoxazasilole: synthesis,properties, and structure

Russian Chemical Bulletin - 2,2-Dimethyl-3-[(4-methylphenyl)sulfonyl]-2,3-dihydro-1,3,2-benzoxazasilole was synthesized by the reaction of N-(2-hydroxyphenyl)-4-methylbenzenesulfonamide with...     

Effects of Divalent Metal Ions on pH-Dependent Hydrolysis of p-Nitrophenyl (E)-(Hydroxyminio) Phosphonoacetate

Abstract

The (E-oxime of phosphonoglyoxylic acid, or (E-troika acid [(E)-l] undergoe: fragmentation leading to phosphorylation of the aqueous solvent at neutral pH and room temperature.[1] In contrast, the corresponding C-methyl ester (a-2 is stable under these mild conditions. Conversion of the unreactive (E)-2 to (E)-1 requires dewthylation a pH 13–14, generating the polyanion of (E-1, which becomes reactive on protonation.[1]     

The Williamson Reaction: A New and Efficient Method for the Alternate Resolution of 2,2'-Bis(bromomethyl)-1,1'-binaphthyl and 1,1'-Binaphthalene-2,2'-diol

Treatment of 2,2'-bis(bromomethyl)-1,1'-binaphthyl [(R,S)-2] with 1,1'-binaphthalene-2,2'-diol (+)-(R)-1 and cesium or potassium carbonate in refluxing acetone, gave the diastereoisomeric dioxacyclophanes (-)-(R,S)-3a and (+)-(R,R)-3b, both obtained in high yield, and the cyclic tetraether (+)-(R,R,R,S)-4 as isolated side product. Boron tribomide-promoted ether cleavage of 3a and 3b gave optically pure (-)-(S)-2 and (+)-(R)-2, respectively, and the recovered diol (+)-(R)-1. Alternatively, the same reaction sequence furnished the resolved diols (-)-(S)-1 and (+)-(R)-1 from (R,S)-1 and (+)-(R)-2, as well as optically pure 2,2'-bis(chloromethyl)-1,1'-binaphthyl (+)-(R)-5 from the racemic dibromide (R,S)-2 by using boron trichloride for ether cleavage.     

Metal-dependent reactions of bulky metal(II) amides M[N(SiMe3)2]2 with 3,3'-disubstituted binaphthols (HO)2C20H10(SiR3)2-3,3': selective conversion of one equivalent -OH group to a silyl ether -OSiMe3

The outcome of the reaction of the bulky metal(II) amides M[N(SiMe3)2]2. nTHF (M = Be, Zn, Ge, Sn, n = 0; M = Mg, Ca, n = 2) with (R)-3,3'-bis(trimethylsilyl)-1,1'-bi-2,2'-naphthol ((R)-1) or (S)-3,3'-bis(dimethylphenylsilyl)-1,1'-bi-2,2'-naphthol ((S)-9) depends on the identity of the metal and the nature of the 3,3'-substituents. When M = Be, Zn, or Ge, these amides serve as useful silylation agents that convert only one of the equivalent hydroxyl groups of the binaphthol (R)-1 to a trimethylsilyl ether, whereas the reactions of (R)-1 with the Mg, Ca, or Sn amides generate a polynuclear complex. The reaction pathway for these interconversions was qualitatively monitored using NMR ((1)H and (9)Be) spectroscopy. Treatment of Ge[N(SiMe3)2] 2 with (S)-9 yields both a silyl ether and the chelated germanium(II) binaphthoxide (S)-[Ge{O2C20H10(SiMe2Ph)2-3,3'}{NH3}], which was structurally characterized.     

Direct, nucleophilic radiosynthesis of [(18)F]trifluoroalkyl tosylates: improved labelling procedures

A rapid and efficient protocol to afford the title compound 2-[(18)F]-fluoro-2,2-difluoroethyl tosylate ([(18)F]7b) is described. Starting from [(18)F]fluoride ion, labelling reagent 7b was obtained in good yields and a high specific radioactivity. Compound ([(18)F]7b) was then used to synthesise a prospective radiotracer for PET-imaging in dementia.     

Early transition metal complexes bearing a C-capped tris(phenolate) ligand incorporating a pendant imine arm: synthesis, structure, and ethylene polymerization behavior

The ligand 3-[2,2'-methylenebis(4,6-di- tert-butylphenol)-5- tert-butylsalicylidene-(2,6-diisopropyl)phenylimine] (L(1)H 3) was reacted with MCl 4 (M = Ti, Zr) or MCl 5 (M = Nb, Ta) to give complexes of the type [MCl 2(L(1)H 2) 2] (M = Ti (1); Zr (2)), [NbCl 3( L (1)H)] (3), or [TaCl 4(L(1)H 2)] (4), respectively. Single crystal X-ray diffraction of 1- 4 revealed common "iminium" species resulting in zwitterionic complexes. Reaction of [V(N p-tol)(O n-Pr) 3] with L (1)H3 afforded [{(VN p-tol)(L(1)H)} 2(mu-O n-Pr)2] (5), and a second complex [(VO) 2(mu-O)(L(3)H) 2] (6)(L(3)H being derived from 3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene- p-tolylimine]). The condensation reaction between 3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butyl-2-hydroxybenzaldehyde] (L(0)H 3) and o-phenylenediamine (1,2-diaminobenzene) afforded two products: a pseudo-16-membered hydrogen bonded macrocyclic structure {1,2-bis-3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-benzyldiimine]} (L(5)H6), or the benzimidazolyl bearing ligand (L(6)H 3). The reaction of L (5)H6 or L(6)H 3 with [VO(O n-Pr) 3] under varying conditions produced the complexes [(VO)(L(5)H 4)] (7), [(VO) 2(L(5)H)] (8), or [VO(L(6)H 2) 2] (9). L (0)H 3 was reacted with a number of anilines to give the proligands {3-[2,2'-methylenebis(4,6-di- tert-butylphenol)-5-tert-butylsalicylidene-R-imine]}, where R = NC 6H 5 (L(2)H3), NC 6H 4-Me (L(3)H 3), and NC 6H 2-Me 3 (L(4)H 3). Reactions of these ligands with [VO(O n-Pr) 3] formed bischelating complexes of the form [(VO)(L(2-4)H 2)2] (10, 11, and 12, respectively). The reaction of L (1)H 3 with trimethylaluminum led to a bis-aluminum complex {(AlMe 2)[AlMe(NCMe)] L (1)} (13). The ability of complexes 1-12 to polymerize ethylene in the presence of an organoaluminum cocatalyst was investigated. Procatalysts 1 and 2 were found to produce negligible activities in the presence of dimethylaluminum chloride (DMAC) and the reactivator ethyltrichloroacetate (ETA), whereas 3 and 4 were found to be completely inactive for polymerization using a variety of different organoaluminum cocatalysts. Using the combination of DMAC and ETA, complexes 5-12 were found to be highly active catalysts; in all cases, the polymer formed was of high molecular weight linear polyethylene.     

Synthesis and properties of chiral ammonium-based ionic liquids

New chiral ammonium-based ionic liquids containing the (1R,2S,5R)-(-)-menthyl group can be easily and efficiently prepared under ambient conditions. The preparation and characterization of trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium salts is reported. The salts have been demonstrated to be air- and moisture-stable under ambient conditions and can be readily used in a variety of standard experimental procedures. The single-crystal X-ray structure of butyldimethyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride has been determined. The chiral, room-temperature ionic liquids have been characterized by physical properties such as specific rotation, density, viscosity, thermal degradation, and glass transition temperature. Trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride prototype ionic liquids have also been found to exhibit strong antimicrobial and high antielectrostatic activities.     

Asymmetric hydrogen-transfer hydrogenation on rhodium(I) complexes with new optically active salen ligands derived from (4<Emphasis Type="Italic">S</Emphasis>,5<Emphasis Type="Italic">S</Emphasis>)-4,5-bis(aminomethyl)-2,2-dimethyl-1,3-dioxolane

New optically active C ₂-symmetric salen-type ligands were synthesized on the basis of (4S,5S)-4,5-bis(aminomethyl)-2,2-dimethyl-1,3-dioxolane. These ligands were used to obtain cationic (trifluoromethanesulfonate) and neutral (chloride) rhodium(I) complexes with [(4S,5S)-2,2-dimethyl-5-{[(E)-pyridin-2-ylmethylidene]aminomethyl}-1,3-dioxolan-4-yl]-N-[(E)-pyridin-2-ylmethylidene]methanamine and [2,2-dimethyl-5-{[(E)-quinolin-2-ylmethylidene]aminomethyl}-1,3-dioxolan-4-yl]-N-[(E)-quinolin-2-ylmethylidene] methanamine. The latter complex ensured preparation of (S)-2-phenylethanol with an optical yield of 34.8% by transfer hydrogenation of acetophenone.     

含平面手性和中心手性双手性因素化合物的合成及应用

[2,2]对二环苯经甲酰化、缩合、拆分得到（Rp）-4-甲酰基[2,2]对二环苯,再与L-亮氨酸的衍生物二齿手性氨基醇经缩合、还原得到由平面手性和中心手性因素构建的化合物（Rp,S）-1,1-二苯基-2-{[2,2]对二环苯基-甲氨基}-4-甲基戊醇.产物结构经IR、MS和1H NMR等进行了表征.用1H NMR考察了其作为主体对客体手性羧酸衍生物消旋体的手性识别能力.     

2, 2'-bis(diphenylphosphino)-1, 1'-binaphthyl(binap) : A new atropisomeric bis(triaryl)phosphine. synthesis and its use in the rh(l)-catalyzed asymmetric hydrogenation of α-(acylamino)acrylic acids

Racemic 2, 2'-bis(diphenylphosphino)-l, 1'-binaphthyl has been synthesized from 2, 2'-dihydroxy-l, l'-binaphthyl in two steps and resolved into optically pure (R)-(+) and (S) (-) enantiomers by the use of (+)-di-μ-chlorobis[(S)-N,N-dimethyl-α-phenylethylamine-2C,N]dipalladium. This new axially dissymmetric bis(triaryl)phosphine serves as an excellent ligand for Rh(l)-catalyzed asymmetric hydrogenations of α-(acylamino) acrylic acids or esters. Factors controlling the enantioselectivity and mechanistic aspects are discussed on the basis of the ³¹P-NMR measurements