Synthesis of 2-Arylbenzofuran: Confirmation of the Structure of Gnetifolin A

GnethelinAu'asisolatedfromGnetumparvghlium(Warb.)C.Y.Chengb}'Lietal.'ItSstructUrextasproPosedpre\'iousl}'as2-(3.5allhydroxT4-methomphen}l)-3-methony-5-hydrox3-benLzofiiran(l).Aner9'nthesisofset1eralanalogsofStrUctUre(l),theStrUCtUrofGnetjfolinAseemstobenustakenanduasrerisedas2K3-5allhydrOny4-methomphenyl)4-methoxy-5-hvdrowtenzofuran(2).=Inordertoconfirmthisrer4ndmCtUranddevelopaversahlewtehcrouteforthe9-nthesisofGnetjfolinAandanalogs,2T-edSyl4-methoxy-5-hydrotwllZofuran(3)u'asselec…     

Chiral Synthesis of the Key Intermediate of Diterpenoids

(-)-Methyl(4R,5SloR)-l4-methoxyPodocmpa-8,ll,l3-triene-l9-oate(I)isthekeyintermediateforsynthesesofditerpenoidssuchaskaurenoicacid(3),kaur-l6-en-l9-ol(4),monoginol(5)('),aswellasC,,-diterpenealkaloidssuchasveachine(6),garryine(7)andatisine(8)(=).TheracemicsynthesisofthisintermediatewasdonebyK.Morietar'),butthechiralsynthesishasnotbeenreported.Herewepresentthechiralsynthesisofthiskeyintermediatefrom(R)-(+)-2-methyl-2-(2'-nitrovinyl)-5-vaierolactone(2).2wassynthesizedaccordingtoliterattirmeth…     

Studies on the Syntheses of the Side Chains of Brassinolide and Dolicholide

(4R,5S)-2,2-Dimethyl-4-(1',2'-dimethylpropyl)-5-(1'-bromoethyl)--1,3-dioxolane(15) with the side chain of brassinolide and (4R, 5S)--2, 2-dimethyl-4-(l'-methylene-2'-methylpropyl)-5-(1'-bromoethyl) 1,3-dioxolane(14) with the side chain of dolicholide were first synthesized through 11 and 10 stepes from D-mannitol respectively. All of the intermediates 7-13 were first synthesized too.     

CIDNP of Diecyl Peroxides Studies on the Kinetics of Decomposition of Diacyl Peiroxides Ⅷ in the Decomposition of Diacyl Peroxides

H CIDNP spectra recorded during the decomposition of aliphatic diacyl peroxides ((RCOO)2 R=n-C H (1),n-c5H11(2)) in ODCB in the presence of scavengers,such as I2C2H5I,(CH3)2CHI,and CH2=CHCH2 Br show multiplet effect for the scavenged products,RX(X=Br,I) and for disproportionation products,R-H.The reactionmechanism is discussed in terms of radical pair theory.     

Preparation of Polystryenylphosphonous Acid of Low Polymerization Degree and Influence of Initiators upon the Free Radical Reaction Mechanism

The polystyrenylphosphonous acid (PSPA) of low polymerization degress was prepared with one step reaction. The reaction mechanism was changed with different initiators. For the reaction with AIBN or BPO as the initiator, therer are 2 or 3 serives of radical reaction chains and 5 or 9 series of polystyrenyl products. The main products are PSPA without or with the fragment of the initiator H[CH(C6H5)-CH2]n-PO2H2 and C6H5CO2-[CH2CH(C6H5)]n-PO2H2 respectively.     

Non-isothermal Kinetics of the Thermal Decomposition of 3-Nitro-1,2,4-triazol-5-one Magnesium Complex

Introduction3 Nitro 1,2 ,4 triazol 5 one (NTO)metalcomplexeshavemanyspecialstructuresandsomepotentialusesinammunition .1 4 Wepreviouslypreparedanddeterminedthecrystalstructureofitsmagnesiumcomplex ,5andinthispaper ,wediscusseditsthermalbehaviorbyDSCandTG/DTGtechniquesandstudieditsnon isothermalkineticsbythemeansoftheKissingermethod ,theOzawamethod ,thedifferentialmethodandtheintegralmethod .ExperimentalSample[Mg(H2 O) 6 ](NTO) 2 ·2H2 Owaspreparedasfollows :AcalculatedamountofMg(OH…     

Syntheses, properties and structures of copper and nickel complexes of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate

The reaction of CuCl2-2H2O or NiCl2.6H2O with K2(C5H6S4) [potassium salt of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]- or [Ni(C5H6S4)2]- as the tetrabutylammonium salt. Both complexes show characteristic IR and UV-Vis absorptions of transition metal dithiolenes. Cyclic voltammograms contain two waves indicating a two step electrochemical procedure [M(C5H6S4)2]0 = [M(C5H6S4)2]1-= [M(C5H6S4)2]2-. Single crystal structure study has been carried out on the nickel complex. Crystal of [Bu4N][Ni(C5H6S4)2] belongs to monoclinic space group P21/c with a=17.576(5), 6=10.883(2), c=17.773(4) A,B=91.07(2)0, Z=4, and o(calcd.)=1.348 g/cm3. Final result is R=0.059 for 2959 reflections. The NiS4 core exhibits square planar coordination with average Ni-S bond length of 2.134(5) A. There are not anion pairs in crystal. The anions stack along a and c axes while the cations intercalate in them. The nearest S-S contact is 4.429 A. The solid powder ESR s     

Spectrophotometric Investigation of Cadmium Complex Solutionwith m-Bromobenzenediazoaminoazobenzene

Therearemanyspectrophotometricmethodsforthedeterminationofcadmiumsuchaswiththefollowingligandsorchromogenicagents:cadions',5-CI-9-PAN',di-2-pyridylmethanone-2-(5-nitropyridyl)bydrazone3andsoon.InourIaboratory,thesynthesisofanewchromogenicreagent,m-bromobenzenediazoaminoazobenzene(m-BBDA)wasmadeanditsstructureisasfollowsmItwasfoundtobesensitiveforthecomplexationwithCd(II)atPHover12.Themaximalabsorptionofthecomplexproductisat480urnbutthatoftheligandisat560urninbasicsolution.Thenon-ionicsur…     

Synthesis and Novel Properties of Alkyl Thiphosporamidate Derivatives of Nucleosides

Novel alkyl thiophosphoramidate derivatives of nucleosde analogues(5) have been prepared by phosphochloridothioate chemistry.O-Isopropyl 2‘,3‘-O-isopropylidene uridine-5‘-yl N-thiophosphoryl threonine and serine methyl esters(5a and 5b )underwent the intramolecular catalyzed hydrolysis reaction.     

Syntheses and Crystal Structures of Benzyl-and Cyclopentyl-Cyclopentadienyl Sodium Tetrahydrofuranate Complexes

The present paper covers syntheses and crystal structures of benzyl- and cy-clopentyl-cyclopentadienyl sodium tetrahydrofuranate complexes C6H5CH2C5H4Na·THF (1) and C5H9C5H4Na°THF (2). X-ray diffraction data of the title compounds were collected at a low temperature (about 210K). Structures of both the crystals belong to monoclinic space group P21/n with α=0. 9316(3) nm, b=1. 5161(4) nm, c= 0.9791(3) nm, β=91. 06(3)°Z=4 for (1) and α=1. 6120(7) nm, b=0. 9370(3) nm, c=1. 8475(7) nm, β=109.52(3)°Z = 8 for (2). Both structures were solved by using direct methods and refined by block-matrix least-squares to final values of R = 0. 044 for 520 observed reflections (1) and R = 0. 067 for 921 observed reflections (2). In the crystals the tetrahydrofuranate complexes C6H5CH2C5H4Na·THF and C5H9C5H4Na·THF adopt a puckered chain structure with η5-(C6H5CH2)C5H4 and η5-(C5H9)C5H4 rings connected by a bridge Na (THF) unit.     

Synthesis and Crystal Structure of the Perchlorate Salt of Diprotonated 2,3-Di-2-pyridyl-5-nitroquinoxaline

<正>The diprotonated perchlorate salt of 2,3-di-2-pyridyl-5-nitroquinoxaline [C18H13N5O2](ClO4)2·(CH3OH)·(C2H5OH) has been synthesized and characterized by elemental analysis, IR and NMR spectra. X-ray diffraction analysis at room temperature indicates that the title compound (C21H23N5O12Cl2, Mr = 608.34) crystallizes in triclinic, space group P 1 with a = 7.992(8), b = 12.82(1), c = 13.42(1) A, α = 104.77(2),β = 97.84(2), r= 95.48(2)°, V= 1305(2) A3, Z = 2,DC= 1.549 g/cm3, F(000) = 628 and μ(MoKα) = 0.317 mm-1. The final R and wR factors are 0.0566 and 0.1016, respectively with 4325 independent reflections. The quinoxaline ring makes the dihedral angles of 44.2(2) and 33.9(5)° with two protonated pyridine rings whose dihedral angle is 48.1(6)°. The favored orientation of two protonated pyridine rings is that thek N atoms are opposite to each other. There exist intra- and inter-molecular N-H…O hydrogen bonds and π…π interactions which stabilize the structure further.     

Synthesis of Imidazole Cyclophane as Ligand of Binuclear Metalloprotein Models

Theelucidationofthemechanismbywhichthedicoppermetalloproteinhemocyanin1bindsandtransportsdioxygencontmuestobeatopicofgreatmterest.Modelcompounds~idrigtheactionofhemOCyatriandrelatedmetalloenZymehavebeendesignedandsyntheslzedbyseveralpeups.2-4Mo8tofthemusedbis(Pyridine),5bis(Pyrazole),6bts(benzforidazole)7andbistwine)8asllgands,butmodelswithbiologicanYrelevantimidazoleareveryseldom.Sincetwoorthreehistidinere8iduesbindtoeacheopperintheaCtivesitesofdicoppermetalloproteins,thebinudearllgandscon…     

Preparation and spectroscopic properties of 2'''',5''''-dideoxynucleosidylcobalamins

Two new coenzyme B12 analogues, 2',5'-dideoxycytidylcobalamin (2a) and 2',5'-dide-oxyuridinylcobalamin (2b), and two others, 2',5'-dideoxyadenosylcobalamin (2c), and 5'-deoxy-thymidylcobalamin (2d) were prepared by an improved method. All the four analogues were investigated by UV-vis and 2D 1H NMR spectroscopy. The comparisons and discussion about their spectroscopic properties were done.     

Crystal Structure of Derivative of H_4′-NOBIN and the Applications in Hetero-Diels-Alder Reaction

Novel Schiff bases of H4′-NOBIN 5a and 5b were synthesized by condensation of 3 with aldehydes. Compound 5b was structurally characterized by single-crystal X-ray diffraction. The asymmetric hetero-Diels-Alder reactions were carried out with high yields and good enan-tioselectivities in the presence of Ti-(S)-5a complex as catalyst. Crystallographic data for 5b: C27H22BrNO, Mr = 456.37, triclinic, space group P1 with a = 9.1618(2), b = 10.3836(2), c = 12.7718(2), α = 105.4860(10),β = 94.6360(10), γ = 108.4610(10)o, V = 1092.32(4)3, Z = 2, Dc = 1.388 g/cm3, μ = 1.900 mm-1, F(000) = 468, R = 0.0476 and wR = 0.1248 for 3092 observed reflections (Ⅰ > 2σ(Ⅰ)).     

Synthesis and Electrochemical Properties of a New Tetraazamacrocyclic Complex of Silver (Ⅰ)

Themetalmacrocycliccomplexeswiththeirunusualoxidationstateshaveattractedmuchinterest.Silver(Il)andsi1ver(IlI)compoundsareusuallyunstab1eduetotheirstrongoxidation.Butsometetraazamacrocyclicligandscandirectlygivestablecom-plexesofsiIver(Il)throughdisproportionatedreactionofsilver(I).12fIere,wereportthesynthesisandeIectrochemicalbehaviorofanewsilver(Il)com-plexAgL(CIO')2(L=5,7,l2,l4-tetraethyl-5,l2-dimethyl-l,4,8,ll-tetraazacyclotetradec-4,l1-diene).Therelativeinformationaboutothersilver(1I…     

Adsorptive Stripping Voltammetric Study of the Enhancement of Copper(Ⅱ) in Phosphate and Carbonate media and in the Presence of Silicate

1.InteductionAdsorPtivestriPPingvoltanUnetry(AdSV)isasensitivendhandyel~talalldevelopeinrecentyears[ll.~,mOStarheS~oneboo~candmetal-owicligandco~,whichcanbeadsoboonthesurfaCeOfeledreadilI21,e.g.2deldebontofCU(II)wasbbtalnedwithitsdi~lglyositall3a].Thedsrptwbooftwleino~cco~OfIDetalshavseldOmareedattentionWAn~tomp'thereareoulytwoinowiccompounwhichhavbenmprtedtohavthepowerOfadsorption(sulfide[4])oradsorptiveeIthanCemen(dspe,5hmesI3b,5l).AlthoUghhigherenhance-mentscanbereachedwhenhCxam…     

Modification of Norditerpenoid Alkaloids:Ⅱ.A Simple andConvenient Preparation of the Imine Derivatives of Norditerpenoid Alkaloids

Interestthenloditlcationofthenorditerpenoidalkaloidsledustopreparationoftheiminederivatives.Preparationmethodsoftheimmeshavebeensummed.includingoxidationa"ithCrO,/pyridine=,rearrangementofchloroamines3andheatingsomeoxazolidine-containingorhavingO.N-mixednorditerpenoidalkaloidssuchasisoatisine1'andajaconine2',withAc=O-pyridine.Inaddition.oxidationof3'withPh(OAc).isalsousedtarthispurpose.In1995,Fuente,elalpreparedanimine5(21%)startingfromperegrine4byoxidationofKMnO./acetone-H,O(2;1)'.Inthe…     

Reaction of Phenylethyne with 2,4-Pentanedione in the Presence of Manganese(Ⅲ) Acetate and Oxygen

WerecentlyrePOrtedmanganese(III)acetate-mediatedoxidatheftee-ndtalCycliZaionofalkeneswith1,3-diones[l-3],o-ketoeSters[4,51andaretoacetamjdesI6]inthepresenceofmolecularoxygenthatyteldedl,2-dioxan-3-olsingoodytelds.Asindlarreachonwasinveedgaedonalkynes,whichgaverisetonovelheterOCyliccomPOundsHereinwedescribetheresu1tS(Schemel)WhenthereachonofDhenVethVne(l)with2,4-pentanedione(2)wncAnedoutinthepresenceacetyl-2-methyl-5-phenylfuran(5)(Tablel,entryl),ThestructUralassigIUnentSarebasedonthe…     

Studies on the solid state reactions of coordination conpounds——XLⅤⅢ.The effect of KSCN on the thermal decomposition of cobalt(Ⅲ)-ammine complexes

The evolved gaseous analysis (EGA),infrared spectra,and XRD have been appliedto the study of solid state reactions of KSCN with five cobalt(Ⅲ)-ammine complexes:[Co-(NH_3)_5N_3]Cl_2,[Co(NH_3)_5(NO_2)]Cl_2,[Co(NH_3)_5(H_2O)]Cl_3,[Co(NH_3)_5Cl]Cl_2,and [Co(NH_3)_6]Cl_3in a hydrogen atmosphere.It is found that the existence of KSCN shifts the thermal decom-position of these complexes to a lower temperature.The corresponding peak temperatures arenear 140℃.The effect of KSCN is discussed and kinetic parameters of deammine reactionsare calculated.     

Influence of Aging Time on the Properties of Precursors of CuO／ZnO Catalysts for Methanol Synthesis

The aging process of pure copper precursors and copper-zinc binary precursors were studied by XRD, TG-DTG and TPR techniques. The catalytic activity and stability of CuO/ZnO were tested using fixed-bed flow reactor, and the physical properties of the catalysts and Cu species were characterized with N2 adsorption and N2O passivation method, respectively. For the Cu-Zn binary system prepared at the precipitating condition of pH=8.0 and temperature=80℃, the initial phase was a mixture of copper nitrate hydroxide Cu2(NO3)(OH)3, georgeite and hydrozincite Zn5(CO3)2(OH)6. By increasing the duration of its aging time, the phase of Cu2(NO3)(OH)2 first transited to georgeite, and then interdiffused into Zns(CO3)2(OH)6 and resulted in two new phases: rosasite (Cu,Zn)2CO3(OH)2 and aurichalcite (Zn,Cu)5(CO3)2(OH)6. The former phase was much easier to be formed than the latter one, while the latter phase was more responsible for the activity of methanol synthesis than the former one. It is found that the composition and structure of the precursors altered obviously after the colour transition point. The experimental results showed that methanol synthesis is a structure-sensitive catalytic reaction.