Asymmetric Synthesis of （R）- and （S）-Moprolol

A simple and effective procedure for the enantioselective synthesis of （R）- and （S）-moprolol was described. The key step was the asymmetric synthesis of enantiopure （R）- and （S）-guaifenesin, which were synthesized from enantioenriched （R）-3-chloro-l,2-propanediol and （S）-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-Co^Ⅲ complex. The e.e. values of both the optical compounds were above 98%, and the chemical structures of the target compounds were confirmed by ^1H NMR, ^13C NMR, IR, and MS.     

Diverse synthesis of the C ring fragment of bryostatins via Zn/Cu-promoted conjugate addition of α-hydroxy iodide with enone

A convergent approach to 1,5-hydroxy ketones,the general precursors for constructing the C ring of bryostatins,has been developed via a Zn/Cu-promoted conjugate addition of a-hydroxy iodides with enones.The reaction leads to direct formation of the C21-C22 bond and tolerates diverse functionalities at the C17-,C18-and C24-positions.The approach also enables a more concise synthesis of the known C ring intermediate(10 longest linear steps and 14 total steps),in contrast to its previous synthesis(17 longest linear steps and 22 total steps) in our total synthesis of bryostatin 8.     

First total synthesis of 10α-hydroxy-4-muurolen-3-one and its C10-isomer

An efficient synthetic route to muurolane type sesquiterpenes starting from （R）-carvone, employing allylic diazene rearrangement and the ring closing methesis （RCM） reaction as key steps, is described. The first asymmetric total synthesis of （-）-10α- hydroxy-4-muurolen-3-one 11 and （-）-10β-hydroxy-4-muurolen-3-one C was accomplished. Through the total synthesis, the absolute configurations of the natural products A, B and C were established.     

Crystal Structures and Theoretical Calculation of Zn（Ⅱ） and Cu（Ⅱ） Supramolecular Complexes Based on Macrocyclic Triamine Ligand 1,4,7-Triazacyclodecane （tacd）

Two supramolecular complexes [Zn（tacd）2]（C6H8O4）·6H2O（1） and [Cu（tacd）2]Cl2·4H2O（2） were synthesized and characterized by elemental analysis, IR spectra, TGA and single-crystal X-ray diffraction analysis. The crystal structure showed that the metal ions in complexes 1 and 2 had similar coordination circumstance. But for the complex 2, it formed a novel two-dimensional supramolecular network with 12-membered rings and four-membered rings via hydrogen bond interaction. The thermal gravimetric analyses indicated that the two complexes had similar steps of weight-loss. On the basis of experiment, the two complexes were calculated by DFT-B3LYP/6-31G（d） in Gaussian 03. The results of calculation are in good agreement with the experiment.     

Effect of Mn（Ⅱ） and Ce（Ⅳ） Ions on the Oxidation of Lactic Acid by Chromic Acid

The kinetics and mechanism of lactic acid oxidation in the presence of Mn（Ⅱ） and Ce（Ⅳ） ions by chromic acid were studied spectrophotometrically. The oxidation of lactic acid by Cr（Ⅵ） was found to proceed in two measurable steps, both of which gave pyruvic acid as the primary product in the absence of Mn（Ⅱ）.2Cr（Ⅵ）＋2CH3CHOHCOOH→2CH3COCOOH＋Cr（Ⅴ）＋C（Ⅲ） Cr（V）＋CH3CHOHCOOH→Cr（Ⅲ）＋CH3COCOOHThe observed kinetics was explained due to the catalytic and inhibitory effects of Mn（Ⅱ） and Ce（Ⅳ） on the lactic acid oxidation by Cr（Ⅵ）. The reactivity of lactic acid depends upon the experimental conditions. It acts as a two- or three- equivalent reducing agent in the absence or presence of Mn（Ⅱ）. It was examined that Cr（Ⅲ） products resulting from the direct reduction of Cr（Ⅵ） by three-equivalent reducing agents. The oxidation of lactic acid follows the complex order kinetics with respect to [lactic acid]. The activation parameters Eo, △H^#, and AS^# were calculated and discussed.     

（Salen）Ti（Ⅳ）-Catalyzed Asymmetric Ring-opening of meso Epoxides Using Dithiophosphorus Acid as the Nucleophile

The asymmetric ring-opening of epoxides with dithiophosphorus acids catalyzed by a （salen）Ti（Ⅳ） complex formed in situ from the reaction of Ti（OPr-i）4 and the chiral Schiff base derived from （1R,2R）-（＋）-diaminocyclohexane was realized. The resulting products were obtained with low to good enantioselectivity （up to 73% ee）.     

Solution Structure and Behavior of Benzophenone-based Achiral Bisphosphine Ligands in Noyori-Type Ru（Ⅱ）-Catalysts

We herein report on solution structural studies of Ru^Ⅱ catalysts （3a, 9） composed of achiral bisphosphine ligands （4, 8） and the enantiopure 1,2-diphenylethylenediamine （DPEN）. Complete chiral induction from enantiopure （R,R）-DPEN to achiral bisphosphine ligand 3a was observed in solution, with the complex adopting a single, stable and non-fluxional （even at 70 ℃） configuration. The coordination of the C=O moiety in 4 to the cationic Run center is considered to be of key importance in providing the higher thermodynamic and kinetic rotation barrier for the flexible bisphosphine ligand in the complex. The obtained enantioselectivity （91% enantiomeric excess） and sense of chiral induction in the hydrogenation of acetophenone were found to be solely dependent on the chirality of the 1,2-diamine. Consistent with the hydrogenation product, the （R,R）-DPEN induces a M-conformation （fight-handed） chirality for flexible phosphine ligand 4 in the complex, resulting in a 2,2-configuration about the Ru^Ⅱ center.     

First total synthesis of （±）-malaysianone A and （±）-tanariflavanones B

A concise approach for the frst total synthesis of two naturally occurring flavanoids,（）-malaysianone A（1）and（）-tanariflavanones B（2）,has been accomplished with total yields of 12.9%and 10.4%,respectively.The key steps were regioselective deprotection and regioselective synthesis of 5-formaldehyde-8-hydroxy-2-[40-methyl-30-penteneyl]-dihydro-1-benzopyran（8）.     

Phebaclavin A和C的全合成研究

Phebaclavin A （1） and C （2） were synthesized in 60% and 58% total yields over 5 steps from commercially available starting meterials respectively. The synthesis feature was usage of the Wittig reaction twice and solvent-free cyclizing reaction as the key steps.     

Two Chiral Building Blocks for the Stereocontrolled Synthesis of Anti-and Syn-1,3-Diols

During the last decade, chiral building blocks for 1, 3-diols of various configurations have been synthesized and applied widely in the total synthesis of natural polyene macrolide antibiotics1 and 1(, 25-dihydroxyvitamin D3 analogues2,3. The synthesis of the building block has attracted much interest in recent years. Herein, we report the synthesis of two chiral building blocks 1 and 2 in 8 steps and 7 steps respectively, starting from the readily available and inexpensive D (+)-xylose 3 as o…     

A concise formal stereoselective total synthesis of （-）-swainsonine

A short formal stereoselective synthesis of （-）-swainsonine （1） is described. Our synthesis started with the versatile building block （R）-3-benzyloxyglutarimide 5. Through controlled regioselective reduction, Ley＇s-sulfone chemistry （N-α-sulfonylation and ZnCl2-catalyzed N-α-amidovinylation）, an RCM reaction, and an amide reduction, the synthesis of unsaturated indolizidine （8R,8aS）-3 has been achieved in five steps. The indolizidine （8R,8aS）-3 is an advanced intermediate toward the synthesis of （-）-swainsonine （1）.     

Synthesis and Crystal Structure of 1,4,7,10-Tetrakis （2-（（4-hydroxy）phenoxy）ethyl）-1,4,7,10- tetraazacyclododecane

A novel molecule tetra-N-alkylation of cyclen （1,4,7,10-tetraazacyclododecane）, 1,4,7,10-tetrakis（2-（（4-hydroxy）phenoxy）ethyl）-1,4,7,10-tetraazacyclododecane 2, was synthesized and structurally characterized by single-crystal X-ray diffraction. The molecule turned into chiral helical compound crystals grown from EtOH by slow diffusion at room temperature and three of the four hydroquinone groups of the benzene ring formed a g-electron-rich cavity by C-H…π stacking interaction. The crystal belongs to the monoclinic system, space group P21/C with a = 13.9192（9）, b = 13.2871（6）, c = 22.1894（15）A^°, β = 91.4600（10）°, V = 4102.5（4）A^°3, Z = 4, Dc = 1.219 g/cm^3, C40H52N4O8, Mr = 752.89, F（000） = 1616,μ = 0.088 mm^-1, MoKa radiation （λ = 0.71073）, R = 0.0578 and wR = 0.1389 for 5588 observed reflections with I 〉 2σ（I）. Moreover, compound 2 was characterized with ^1H NMR, ^13C NMR, IR spectra and MS.     

Transitional Process of Ploy（N-isopropylacrylamide） in Deuterated Solution

The fast phase-transitional process of ploy（N-isopropylacrylamide） （PNIPAM） in deuterated solution was studied by laser induced temperature jump technique combined with time-resolved mid-infrared absorbance difference spectroscopy on nanosecond level. The multi-peaks of amide I＇band of PNIPAM among the energy range of 1565-1700 cm^-1 was experimentally resolved to three groups （i, ii, iii） for the first time, while the distinct threestage procedure in the phase transitional process of long-chain PNIPAM was observed firstly too. Furthermore, proper assignments were also made for the three group peaks in amide I＇band and the three steps in the kinetics process of long-chain PNIPAM.     

Pincer iridium（Ⅲ）-catalyzed enantioselective C（sp3）-H functionalization via carbenoid C–H insertion of 3-diazooxindoles with 1,4-cyclohexadiene

The asymmetric carbenoid C–H insertion of 3-diazooxindoles into 1,4-cyclohexadiene has been accomplished in the presence of chiral bis(imidazoline) NCN pincer iridium(Ⅲ) complexes as the catalysts. With a catalyst loading of 0.5 mol%, the reactions proceeded smoothly at 0℃ to afford a variety of chiral 3-substituted oxindoles in good yields with moderate to excellent enantioselectivities(up to 99% ee). The protocol exhibits good functional group tolerance with respect to 3-diazooxindoles and is ...     

First Synthesis of （＋）-2,14-Deoxyalatol from α-Santonin

A novel and general approach for synthesis of the multi-oxygenated dihydrofuran sesquiterpenes has been developed starting from santonin. The key steps involve: the strategic acid-catalyzed double-bond shifting affording 4, the novel base-promoted epoxide rearrangement of 5 generating two key functionals (the C5-OH and the Δ^7,11 double bond), and the stereoselective cyclization of tetrahydrofuran ring without pre-controlling the stereochemistry of C-7. As an example of this approach, synthesis of ( )-2,14-deoxyalatol was described in detail.     

Pincer iridium（Ⅲ）-catalyzed enantioselective C（sp3）-H functionalization via carbenoid C–H insertion of 3-diazooxindoles with 1,4-cyclohexadiene

The asymmetric carbenoid C–H insertion of 3-diazooxindoles into 1,4-cyclohexadiene has been accomplished in the presence of chiral bis(imidazoline) NCN pincer iridium(Ⅲ) complexes as the catalysts. With a catalyst loading of 0.5 mol%, the reactions proceeded smoothly at 0℃ to afford a variety of chiral 3-substituted oxindoles in good yields with moderate to excellent enantioselectivities(up to 99% ee). The protocol exhibits good functional group tolerance with respect to 3-diazooxindoles and is ...     

Convenient synthesis of （2S,3R,4R,5S,6R）-2-（3-（4-ethylbenzyl）-4- chlorophenyl）-6-（hydroxymethyl）-tetrahydro- 2H-pyran-3,4,5-triol

A convenient approach for the preparation of （2S,3R,4R,5S,6R）-2-（3-（4-ethylbenzyl）-4-chlorophenyl）-6-（hydroxymethyl）- tetrahydro-2H-pyran-3,4,5-triol I is developed. The target compound via four steps is synthesized from 4-bromo-2-（bromomethyl）- 1-chlorobenzene and the isomers of undesired ortho-products were avoided during the preparation.     

Catalytic enantioselective synthesis of β-amino alcohols by nitrene insertion

Chiral β-amino alcohols are important building blocks for the synthesis of drugs, natural products, chiral auxiliaries, chiral ligands and chiral organocatalysts. The catalytic asymmetric β-amination of alcohols offers a direct strategy to access this class of molecules. Herein, we report a general intramolecular C(sp~3)–H nitrene insertion method for the synthesis of chiral oxazolidin-2-ones as precursors of chiral β-amino alcohols. Specifically, the ring-closing C(sp~3)–H amination of N-benzoyloxycarbamates with 2 mol% of a chiral ruthenium catalyst provides cyclic carbamates in up to 99% yield and with up to 99% ee.The method is applicable to benzylic, allylic, and propargylic C–H bonds and can even be applied to completely non-activated C(sp~3)–H bonds, although with somewhat reduced yields and stereoselectivities. The obtained cyclic carbamates can subsequently be hydrolyzed to obtain chiral β-amino alcohols. The method is very practical as the catalyst can be easily synthesized on a gram scale and can be recycled after the reaction for further use. The synthetic value of the new method is demonstrated with the asymmetric synthesis of a chiral oxazolidin-2-one as intermediate for the synthesis of the natural product aurantioclavine and chiral β-amino alcohols that are intermediates for the synthesis of chiral amino acids, indane-derived chiral Box-ligands, and the natural products dihydrohamacanthin A and dragmacidin A.     

Enantioselective Alkynylation of Benzaldehyde Catalyzed by New Chiral Lewis Acid Ligand: Zinc-Amide Complex

The enantioselective alkynylzinc addition to aldehydes is very useful for the synthesis of chiral propargyl alcohols which are important versatile building blocks of many biologically active compounds and natural products1. A series of chiral oxazolidines were conveniently synthesized from amino acids in three steps with good yields. The use of chiral Lewis acid ligand: zinc-amide complex in situ generated from this oxazolidine with alkylzinc as chiral catalysts for the enantioselective alkyny…     

Synthesis, Characterization and Properties of Poly（aryl amides） Containing Methoxy Substituted Phthalazinone Moiety

A novel aromatic diamine, 1, 2-dihydro-2-（4-aminophenyl）-4-[3-methoxy-4-（4-aminophenoxy）]-2, 3-phthalazin-l-one （OO-DA） containing aza heterocyclic structure was synthesized from the bisphenol-like monomer in two steps and used for preparing new aromatic polyamides with high inherent viscosity of 0.89-1.03 dL.g^-1. The structures of diamine and polymers obtained were confirmed by MS, PT-IR, WAXD and ^1H-NMR. The synthesized polymers exhibited high glass transition temperature in the range of 281-307℃ and good solubility in polar solvents.