Wholly aromatic chiral polyamides bearing pendant phthalimido and L-isoleucine moities

<正>A potential biodegradable and optically active bulky chiral aromatic amide-imidic diacid monomer,(2S,3S)-5-(3- methyl-2-phthalimidylpentanoylarnino)isophthalic acid(7),containing a rigid phthalimide and flexible L-isoleucine pendant group was synthesized in three steps.New aromatic polyamides including pendant phthalimido groups and flexible side spacers have been synthesized by direct polycondensation reaction of equimolar amounts of different aromatic diamines with an optically active diacid 7,using N-methyl-2-pyrrolidone(NMP) as a solvent and triphenyl phosphite/CaCl_2/pyridine as a condensing agent.These polyamides were characterized by FTIR,~1H-NMR spectroscopy,specific rotation, thermogravimetric and elemental analysis.The resulting polymers have inherent viscosities in the range of 0.21-0.45 dL/g. Amino acid existence in this backbone results in optically active polymers.Due to introduction of bulky and flexible groups in these polyamides,they show improved solubility in polar aprotic solvents such as NMP and dimethylacetamide and also good thermal stability(10%weight loss temperatures in excess of 330℃,and char yields at 600℃in nitrogen higher than 62%).     

OPTICAL PHASE CONJUGATION RESPONSE OF PHOTOINDUCED POLYMER FILMS CONTAINING AZOBENZENE MOIETIES WITH CHIRAL GROUP

An optically active monomer containing azobenzene moieties with chiral group (s-2-methyl-butyl), 4-[2-(methacryloyloxy)ethyloxy]-4'-(s-2-methyl-1-butyloxycarbonyl) azobenzene(Ml) was synthesized. Polymer (PMl)possessing optical phase conjugated response was obtained by homopolymerzation of the optically active monomer (Ml)using free radical polymerization. The polymer was very soluble in common solvents and good optical quality films could beeasily fabricated by spin coating. The optical phase conjugated responses of the polymer PM1 were measured by degeneratefour-wave mixing (DFWM). In comparison with polymer containing no chiral group, it was found from the preliminarymeasurement of photoisomeric change that optical phase conjugated response of the PM1 in the long-range order hexagonalsymmetry microstructure could be easily controlled by choosing the appropriate polarization direction of the irradiatingbeams (514.5 nm) and the irradiating number, presumably due to the chiral group in the PM1 molecular structure. For thecase of the polymer investigated here, a chiral group side chain was introduced to increase optical phase conjugated responseintensity with different polarization directions of the irradiating beams, which aims originally at searching for a new photo-ative material.     

Study on Lewis acid promoted condensation of allylalkoxysilanes with (-)-menthyl glyoxylate

Allylalkoxydimethylsilanes (2) condense with (-)-menthyl glyoxylate (3) in the presence of Lewis acid to give optically active menthyl 2-hydroxy-4-pentenoate (7) with optical purity of 31-42%. Factors affecting the yield and de of 7 have been examined. The stereochemistry of transition state of the reaction was discussed.     

Simple and Mild Syntheses of Optically Active 2-（N,N-Dialkylamino）oxazolines

Chloroamidinium salts and α-amino alcohols derived from commercially available tetraalkyl ureas and α-amino acids, respectively, can be used for the syntheses of optically active 2-(N,N-dialkylamino)oxazolines in moderate to excellent yields without any catalyst. It is a simple and mild method for the syntheses of optically active oxazolines     

STUDY ON ASYMMETRIC SYNTHESIS OF 19-NORSTEROIDS SYNTHESIS OF A NEW OPTICALLY ACTIVE SYNTHON, (2R, 3S)-( )-2-ETHYL-2-(3'-OXO-4'-ENE)-AMYL-3-ACETOXY-CYCLOPENTANONE

This paper reports the synthesis of a new optically active synthon 6 for the asymmetricsynthesis of 19-norsteroids. Symmetric trione 9 obtained by the reaction of γ-carbonyl sulfo-xide 12b with 2-cthyl-1, 3-cyclopetanedione 8, was reduced asymmetrically by Saccharomycescerevisiae to (2R,3S)-(-)-14 and subsequently transformed into (2R,3S)-( )-6 by a shortreaction sequence. The absolute configuration of the asymmetrical product, (2R, 3S)-(-)-14,was established by converting it into the known compound (2R, 3S)-( )-17.     

Eco-friendly fast synthesis and thermal degradation of optically active polyamides under microwave accelerating conditions

<正>An optically active bulky aromatic diacid chiral monomer,(2S)-4-[(4-methyl-2-phthalimidylpentanoyl-amino) benzoylamino]isophthalic acid(1),containing a rigid phthalimide and flexible L-leucine pendent group was synthesized in five steps.A fast and clean method for direct polyamidation reaction of monomer 1 with various aromatic diamines under microwave irradiation and conventional heating was performed.The polymerization reactions provided optically active polyamides with high yields and inherent viscosities in the range of 0.36-0.74 dL/g.Their thermal properties were evaluated by thermogravimetric analysis(TGA) and differential scanning calorimetry.TGA thermograms show that the polymers are thermally stable,10%weight loss temperatures are in excess of 385℃,and char yields at 800℃are higher than 56%.The data obtained from TGA were used to study the kinetics of thermal decomposition of the resulting polymers. The interpretation of kinetic parameters(E,ΔH,ΔS andΔG) of thermal decomposition stages was evaluated using Coats and Redfern equation.     

Synthesis of novel chiral compounds of purine and pyrimidine bases

The physiologically active groups such as purine and pyrimidine bases are introduced to the asymmetric ynthesis. The optically pure compounds bearing purine and pyrimidine bases (5a—5e) were prepared via the asymetric Michael addition reaction of purines and pyrimidines as Michael donators with the chiral source 5-(R)-[(1R, 2S, 5R)-menthyloxy]-2(5H)-furanone (3a), which was prepared from the natural chiral auxiliary (-)-menthol. The synthetic method was studied in detail and the new compounds were identified on the basis of their analytical data and spectroscopic data, such as [α]_D~(20), IR, UV, ~1H NMR, ~(13)C NMR and MS. The absolute configuration of 5a was established by X-ray crystallography. The results provided an efficient synthetic route to chiral purines and pyrimidine analogues, and offered chiral sources for further research on the physiologically active compounds of chiral nucleotides.     

Resolution of 3,3''''-Dioxo-1,1''''(3H,3(H)spirobi[isobenzofuran] -5,6,5''''6''''-tetracarboxylic acid and Optically active Polyimides thereof

Previously, we have reported a novel type of polyimides prepared from 3,3(-dioxo-1,1((3H,3(H)spirobi[isobenzofuran]-5,6,5(,6(-dianhydride 1a and a variety of diamines1. Considering that a spiral compound is planar asymmetry2, we recently studied the resolution of 1, and thereof, synthesized the optically active polyimides. To our knowledge, optically active polyimides containing a planar asymmetric monomers have not been reported thus far. Cinchonidine and cinchonine base were proved to be an…     

Synthesis of New MeO-BIPHEP-type Chiral Diphosphines by an Improved Way

In this paper,a series of new optically active MeO-BIPHEP-type ligands,(S)-6,6'-dimethoxy-2,2'-bis(di-p-alkoxyphenyl-phosphine)-1,1'-biphenyl[(S)-5b—(S)-5e]were prepared and characterized.Starting from thecommercially available triethyl phosphorite and m-bromoanisole,an optically active(S)-6,6'-dimethoxybiphenyl-2,2'-diyl-bis(phosphonic acid diester)was prepared by an improved way and converted to the corresponding dichlo-rides,which was used as a key intermediate to react with p-alkoxybenzenemagnesium bromide or p-alkoxyphenyllithium to directly give the enantiomerically pure diphosphines 5.     

Synthesis of New Bifunctional Bis(oxazolines) and Their Application in the Asymmetric Cyanosilylation of Aromatic Ketones

Catalytic asymmetric synthesis of tertiary cyanohydrins by the addition of cyanide to a wide range of ketones has important synthetic utility, since the resulting optically active cyanohydrins are important intermediates for the synthesis of a variety of valuable classes of chiral compounds. The application of oxazoline in asymmetric cyanosilylation has seldom reported in comparation with other reactions.[1] Recently, polymer-supported pyridine-bis(oxazoline) ytterbium complex was reported to catalyze cyanosilylation of benzaldehyde.     

Crystal Structure of Phenol,2-[4（S）-4-Dihydro-4-benzyl-2-ozazolinyl]

The compound phenol,2-[4(S)-4,5-dihydro-4-phenyl-2-ozazolinyl(1,C15H13NO2) was synthesized with a simple,one step method free of water and air.It was obtained in a moderate yield from the reaction of 2-hydroxybenzonitrile with optically active amino alcohol in chloroben-zene under dry,anaerobic conditions.It belongs to the orthorhombic system,space group P212121 with a = 5.786(5),b = 10.730(5),c = 19.722(5),C15H13NO2,Mr = 239.26,V = 1224.4(12)3,Z = 4 and Dc = 1.298 mg/m3.The final R = 0.0324 for 1627 observed reflections with Ⅰ 2σ(Ⅰ) and Rw = 0.0826 for all data.The structure of compound 1 was determined by X-ray diffraction,NMR and HRMS.     

Synthesis of spiro-cyclopropane derivatives containing multiple chiral centers

Tandem asymmetric double Michael addition/internal nucleophilic substitution of the novel chiral source, 5-(l-menthyloxy)-3-bromo-2(5H)-furanone with nucleophilic alcohol compounds has been investigated. The tandem asymmetric reaction can afford four new stereogenic centers with one reaction and give optically pure spiro-cyclopropane derivatives 5a--5d which are difficult to obtain by routine methods. The synthetic method for 5a--5d was studied in detail and the new compounds were identified on the basis of their analytical data and spectroscopic data, such as [α]~(20),IR,~1H NMR,~(13)C NMR, MS and elementary analysis. The absolute configuration of the sprio [5-l-menthyloxy-3-bromo butyrolactocyclopropane-3″, 3′(4′-methyloxy-5′-menthyloxybutyrolactone)] (5a) was established by X-ray crystallography. The work can provide important synthetic strategy in synthesis of some new optically active spiro-cyclopropane analogues and some biologically active molecules with complex structure.     

An Efficient Synthesis of Highly Optically Active 4-Substituted-2（5H）-furanones from Chiral 3-Bromo-2（5H）-furanone

Highly optically active 4-substituted-2(5H)-furanones 6a-6j were obtained in good yields with de≥98% by the tandem Michael addition/elimination reaction of chiral 3-bromo-2(SH)-furanone (4a), which was conveniently prepared starting from 2-furaldehyde under mild conditions. The products were identified on the basis of their satisfactory elemental analysis and spectroscopic data of IR, UV, ^1H NMR, ^13C NMR and mass spectra. The stereochemistry and absolute configuration of this type of compounds were established by the X-ray crystallographic study. The reaction provided a short and efficient synthesis of the interesting highly optically active 4-subsdtuted-2(5H)-furanones containing an active pyrimidine and a purine base group.     

Optically Active Chiral Auxiliary Benzyloxyphenylglycinol for Preparation of Oxazolidine and Its Derivatives

To investigate the recovery of amino alcohols as chiral auxiliaries, optically active p-benzyloxyphenylglycinol and its corresponding oxazolidine of 1-naphthylcarboxaldehyde were prepared. Grignard additions to the oxazolidine followed by electrophilic quench and acidic hydrolysis afforded an aldehyde( compound 8) (later it was reduced to an alcohol, compound 9) in an excellent enantiomeric excess and a good recovery of the chlral amino alcohol. This research provides a model study of chiral amino alcohols in solid phase asymmetric synthesis.     

POLYMERIZATION OF N,N′-（PYROMELLITOYL）-BIS-L-LEUCINE DIACID CHLORIDE WITH HYDANTOIN DERIVATIVES BY MICROWAVE IRRADIATION

Facile and rapid polycondensation reactions of N,N′-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence of a small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (ηinh), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported.     

Study on the Synthesis of Metabolite CM2 of Clausenamide

Synthesis of the optically active metabolite of clausenamide cm2(3,5-dihydroxy-5-(α-hydroxylbenzyl)-1-methyl-4-benzylpyrrolidin-2-one)from 3-O-acetyl-clausenamide was described.     

Synthesis of Cellulose Tris (4-Methylbenzoate) as Gas Chromatographic Stationary Phase and its Characterization

Cellulose (MC) is the most accessible optically active polymer. Its benzoate and phenylcarbamate derivatives exhibit a high chiral recognition ability for a variety of racemic compounds as chiral stationary phases (CSPs) for high performance liquid chromatography1-3. However, the application of cellulose derivatives in gas chromatography has seldom been reported except that Zou reported cellulose tribenzoate (CTB) which was used as a stationary phase for gas chromatography 4. Cellulose and…     

Copper-Catalyzed Si-H Bond Insertion Polymerization for Synthesis of Optically Active Polyesters Containing Silicon

The synthesis and characterization of chiral polymers with diverse structure remain a long-term challenging research topic.Herein,a copper-catalyzed enantioselective insertion of carbene into Si-H bond was applied to polycondensation,giving a new type of optically active degradable polyesters containing Si-C bond in the main chain.The polymerization features mild condition,broad substrate scope,excellent yields and enantioselectivities.Chiral diols could be obtained via reduction of optically active polyesters.Thermogravimetric analysis indicated these chiral polyesters exhibit good thermal stability.     

Catalytic Enantioselective Reduction of Prochiral Ketones with Chiral Ferrocenyl Amino Alcohols

The asymmetric reduction of prochiral ketones was catalyzed by a class of recoverable and highly stable chiral ferrocenyl amino alcohols derived from natural amino acids to yield optically active secondary alcohols in high chemical yields and moderate to good enantiomeric excesses.     

L-脯氨酸催化下甲基酮和1-芳基-2,2,2-三氟乙酮的不对称Aldol反应

Direct asymmetric aldol addition of methyl ketones to 2,2,2-trifluoro-1-phenylethanone and its ring-substituted derivatives was achieved using L-proline as a chiral promoter. Various optically active β-trifluoromethyl-β-hydroxy ketones were obtained in almost quantitative yields with moderate enantioselectivities up to 64 % ee.