New limonoids from the fruits of Melia toosendan

<正>Two new limonoids,1α-tigloyloxy-3α-acetoxyl-7α-hydroxyl-12α-ethoxyl nimbolinin(1) and lα-benzoyloxy-3α-acetoxyl-7α- hydroxyl-12α-ethoxyl nimbolinin(2),were isolated from the fruits of Melia toosendan.Their structures were established on the basis of various NMR spectroscopic analyses,including 2D-NMR techniques(HSQC,HMBC,NOESY) and HR-ESI-MS.     

The Sulfinatodehalogenation Reaction of α ,α -Difluorobenzyl Halides with Sodium Dithionite

The sulfinatodehalogenation reaction of α,α-difluorobenzyl halides, ArCF2X ( Ar = C6F5, C6H5; X = Br, I ), with sodium dithionite took place readily in aqueous acetonitrile under mild conditions, giving the corresponding sodium sulfinate. The 1:1 adducts were obtained when alkenes were added to the reaction system in some cases.     

Determination of Utratrace Silver Using Surfactant As Sensitizer by Catalytic Near Field Laser Thermal Lens Spectrometry

Thermal lens spectrometry (TLS) is an excellent tool for trace analysis1. TLS allows the detection of absorbances of 10-7～10-8, concentration of ≈ 10-11 mol稬-1 and the analysis of 10-15 L volumes with ≈10-2 absorbing molecules2. Kinetic analysis is playing an increasingly important part in modern analytical chemistry. Therefore, TLS shows much promise in combination with kinetic analysis. However, there are few data on TLS applications in kinetic analysis method so far3～4. A ne…     

Solid-phase Synthesis of-Haloaldehydes from Polymer-supported 4-(Phenylseleno)morpholine

Polymer-supported reagents for organic synthesis are enjoying a renewed popularity with the emergence of combinatorial chemistry in recent years1. 4-(Arylseleno)morpholines formed in situ are useful -seleno-introducing reagents for saturated aldehydes2. -Sele- noaldehydes, as a frequently used intermediates, can be converted into -haloaldehydes by halogenating reaction3. However, organic selenium reagents always have a foul smell and are quite toxic, which is often problematic in organic sy…     

Rh(Ⅱ) and Zn(Ⅱ) co-catalyzed multi-component reaction for the synthesis of vicinal diols

Oxonium ylide intermediates generated fromα-diazocarbonyl compounds and water were trapped by Zn(Ⅱ)-activatedα-dicarbonyl compounds.The reaction gaveα,β-dihydroxyl acid derivatives in moderate yield.     

Chemoselective Bromodecarboxylation of α-Carboxy-α-cinnamoyl Ketene Cyclic Dithioacetals

Introduction α-Oxoketene dithioacetals(compound 1) are versatile synthons for organic synthesis due to their specially structural characteristic, that is, the masked ketene is conjugated with the convertible carbonyl in their molecules[1-8].     

Convenient Synthesis of Substituted Quinoxalines and 2H-Benzo[b][1,4]oxazines in Water

A facile and convenient synthesis method has been developed for substituted quinoxalines and 2H-benzo[b][1,4]oxazines from the reactions of α-bromoketones with benzene-1,2-diamine and 2-aminophenol, respectively, which were catalyzed by tetrabutylammonium bromide(TBAB) in aqueous basic media.     

Investigation of Inclusion Complexes Between α-Cyclodextrin and Ferrocene by ESI-MSn and Cyclic Voltammetry

The inclusion complexes of α-cyclodextrin(α-CD) and FcCO2(CH2)18 (FcSH) and their self-assembled monolayers(SAMs) on gold surface were investigated by electrospray tandem ionization mass spectrometry(ESI-MSn) and cyclic voltammetry, respectively. The interfacial electrochemical response of the SAMs is related to the way in which the inclusion complexes formed.     

INCLUSION COMPLEX FORMATION BETWEEN α-CYCLODEXTRIN AND BIODEGRADABLE COMBLIKE COPOLYMERS WITH POLY(α,β-MALIC ACID) BACKBONES AND mPEG SIDE CHAINS

Inclusion complexes(ICs) composed ofα-cyclodextrins(α-CD) and biodegradable comblike copolymers with poly(α,β-malic acid)(PMA) backbones and methylated poly(ethylene glycol)(mPEG) side chains were prepared by the host-guest reaction.Two series of ICs with mPEG750 and mPEG2000 were prepared.The stoichiometry(EG/CD) of all the ICs in mPEG2000 series was 3.1,no matter what the graft degree was.While in mPEG750 series,the stoichiometry(EG/CD) was very different:it increased with the amount of mPEG decreasing...     

Chiral Phosphine Ligands Derived from Sugars. 14. Crystal Structure of Diphenyl(methyl 4',6'-O-benzylidene-3'-deoxy-α-D-altropyranoside-3-)phosphine Oxide

The crystal structure of the title compound, C26H27O6P, has been determined by single-crystal X-ray diffraction analysis. The crystal is orthorhombic with space group P212121, a=6.154(4), b=17.199(8), c=22.180(3)(A), V=2347.6(A)3, Dc=1.32 g/cm3, F(000)=984, μ=1.5cm-1, Z=4, and final R=0.075 and Rw=0.080 for 1417 reflections (I≥3σ(I)). The X-ray diffraction analysis revealed that the structure of the title compound s similar to that of its parent phosphine and the pyranose and 4, 6-O-benzylidene rings remain distorted chair conformations.     

Crystal Structure of Diethyl 1-(6-methyl-2-benzothia-zolylamino)-2, 4-dichlorophenylmethylphosphonate

１ＩＮＴＲＯＤＵＣＴＩＯＮα Ａｍｉｎｏｐｈｏｓｐｈｏｎｉｃａｃｉｄｓ,ｂｉｏｉｓｏｓｔｅｒｅｓｏｆｎａｔｕｒａｌａｍｉｎｏａｃｉｄｓ,ｈａｖｅａｔｒａｃｔｅｄｍｕｃｈａｔｅｎｔｉｏｎｂｅｃａｕｓｅｔｈｅｙｓｈｏｗｗｉｄｅｂｉｏｌｏｇｉｃａｌａｃｔｉ...     

Chiral Ligands Derived from Carbohydrates. 21.Crystal Structure of Methyl-4,6-O-benzylidene-3-deoxy-3-(salicylideneamino)-α-D-altropyranoside

A new chiral Schiff base derived from carbohydrate, methyl-4,6-O-benzylidene-3- deoxy-3-(salicylideneamino)-α-D-altropyranoside, has been synthesized by reacting methyl 3-ami- no-4,6-O-benzylidene-3-deoxy-α-D-altropyranoside with salicylaldehyde in methanol and charac- terized by IR, 1H NMR, 13C NMR, MS, elemental analysis, and X-ray crystal structure analysis.The crystal belongs to orthorhombic, space group P212121 with a = 8.0856(16), b = 10.786(2), c = 22.690(5) -, V = 1978.8(7) -3, Z = 4, Mr = 385.40, Dc = 1.294 g/cm3, μ = 0.095 mm-1, F(000) = 816, the final R = 0.0379 and wR = 0.0811 for 2597 independent reflections.In the title compound, the pyrano-ring adopts a twisted 1C4 chair conformation.     

SYNTHESIS AND CHARACTERIZATION OF POLYROTAXANES MADE FROM α-CDs THREADED ONTO TRIBLOCK COPOLYMERS WITH PEG AS A CENTRAL AXLE AND FLANKED BY TWO LOW MOLECULAR WEIGHT POLYSTYRENES AS OUTER STOPPERS

A study has been conducted on the synthesis and characterization of a kind of novel polyrotaxanes comprising α cyclodextrins (α-CDs) threaded on triblock copolymers with poly(ethylene glycol) (PEG) as a central axle and flanked by two low molecular weight polystyrenes as outer stoppers.Styrene was allowed to telomerize with polypseudorotaxanes as chain transfer agents made from the self-assembly of a distal thiol-capped PEG with a varying amount of α-CDs in the presence of a redox initiation system at 40℃ in aqueous solutions.The resulting polyrotaxanes were characterized in detail by 1H-NMR,FTIR,XRD,TG and DSC analyses.The findings from the study demonstrated that the low molecular weight polystyrenes were successfully attached to two axle terminals of polypseudorotaxanes,and the number of α-CDs threaded onto the PEG backbone was tunable by varying its molar feeding ratio to some extent,while the polymerization degree of PS nearly remained constant in this radical telomerization process.     

Synthesis, Crystal Structure and Herbicidal Activity of O,O'-Diethyl-N-[2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yloxy)-benzoxyl]-1-amino-benzyl phosphonate

The crystal structure of the title compound (C25H28N5O5P,Mr= 509.49) has been determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group P21/c with a = 13.0726(4), b = 13.4513(4), c = 15.103(1) (A),β = 93.650(1)°, V= 2650.29(14) (A)3, Z= 4, Dc =1.277 g/cm3, F(000) = 1072, μ(MoKα) = 0.147 mm-1, the final R = 0.0748 and wR = 0.1956 for 3186 observed reflections (Ⅰ＞ 2σ(Ⅰ)). The fused triazolopyrimidine system ring is coplanar, the dihedral angles between the triazolopyrimidine and C(1)-C(3)-C(5) phenyl, the triazolopyrimidine and C(17)-C(19)-C(21) phenyl, and the two phenyl rings are 66.87, 58.79 and 80.11°, respectively.contribute to the stability of the structure and result in a three-dimensional framework. The preliminary bioassay indicates that the title compound exhibits moderate herbicidal activity against dicotyledonous plants (Brassica campestris L) at the concentration of 100 mg/L.     

A new approach to the synthesis of α-chlorocycloalkanones

α-Chlorocycloalkanones(Ⅳ) were synthesized from cycloalkanones via potassiumα-oxocycloalkylsulfonates(Ⅱ).A two-step mechanism was proposed to explain the formation ofⅣfromⅡ.     

Ferric Chloride Catalyzed Isomerization and Cyclization of Geraniol, Linalool and Nerol

Geranyl pyrophosphate, linalyl pyrophosphate and neryl pyrophosphate are known to be important precursors for biosynthesis of cyclic terpenoids, and a variety of cationic intermediates have been suggested to be involved in their skeletal rearrangements1. Ferric chloride has recently been used as a Lewis acid to catalyze Friedel-Crafts reactions2, synthesis of esters and acetals3, a-glycosidation of peracetylated sugars4 and cyclization of 2-(trimethylsilylmethyl) pentadienal5. Therefore, i…     

Synthesis of novel chiral phosphine-triazine ligand derived from α-phenylethylamine for Pd-catalyzed asymmetric allylic alkylation

A novel chiral phosphine-triazine ligand was synthesized from chiral model reaction of Pd-catalyzed allylic alkylation of rac-l,3-diphenylprop-2-en-l-yl pivalate with dimethyl malonate, good enantioselectivity (90% e.e.) was obtained by using this ligand.     

A practical synthesis of α-bromo/iodo/chloroketones from olefins under visible-light irradiation conditions

A practical synthesis of α-bromo/iodo/chloroketones from olefins under visible-light irradiation conditions has been developed.In the presence of PhI(OAc)₂ as promoter and under ambient conditions,the reactions of styrenes and triiodomethane undergo the transformation smoothly to deliver the corresponding a-iodoketones without additional photocatalyst in good yields under sunlight irradiation.Mea nwhile,the reactions of styrenes with tribromomethane and trichloromethane generate the desiredα-bromoketones and a-chloroketones in high yields by using Ru(bpy)₃Cl₂ as a photocatalyst under blue LED(450-455 nm) irradiation.