α-Carbonyl Radical Cyclization for the Total Synthesis of Natural Products

Intramolecular radical cyclization reactions are now used routinely to synthesize carbocyclic and heterocyclicstructures. We have reported that α-carbonyl radicals 1, generated from the corresponding iodo ketones or enones,underwent intramolecular radical cyclization smoothly to afford products 2. [1,2]     

An Expedient Approach to the Benzopyran Core: Application to Synthesis of the Natural Products(±)-Xyloketals and(±)-Alboatrin

A mild and efficient protocol for the synthesis of the benzopyran ring has been described and a series of chromans compounds is reported, the yield is from 72% to 95%. The diadduct tended to angular product and showed good regioselectivity. This strategy was applied for the benzopyran derived natural products (±)‐xyloketals and (±)‐alboatrin. The crystal of compound 9 exhibited centro‐symmetric space group, containing two isomers in one unit. The relative configurations were 1R,10R,15S and 34S,22R,30S, respectively.     

Decarboxylative Cyclization of Allylic Cyclic Carbamates: Mechanism Studies and Applications to the Synthesis of Natural Products

The mechanism of decarboxylative cyclization of allylic cyclic carbamates 1 leading to 2-substituted △~3-piperidines and-pyrrolidines, as well as its applications to the total synthesis of (--)codonopsine, are described.     

Methylene C(sp3)−H Arylation Enables the Stereoselective Synthesis and Structure Revision of Indidene Natural Products

The divergent synthesis of two indane polyketides of the indidene family, namely (±)-indidene A (11 steps, 1.7 %) and (+)-indidene C (13 steps, 1.3 %), is reported. The synthesis of the trans-configured common indane intermediate was enabled by palladium(0)-catalyzed methylene C(sp³)−H arylation, which was performed in both racemic and enantioselective (e.r. 99 : 1) modes. Further elaboration of this common intermediate by nickel-catalyzed dehydrogenative coupling allowed the rapid installation of the aroyl moiety of (±)-indidene A. In parallel, the biphenyl system of (±)- and (+)-indidene C was constructed by Suzuki–Miyaura coupling. These investigations led us to revise the structures of indidenes B and C.     

Synthesis of Natural Products by C−H Functionalization of Heterocycless

Total synthesis is considered by many as the finest combination of art and science. During the last decades, several concepts were proposed for achieving the perfect vision of total synthesis, such as atom economy, step economy, or redox economy. In this context, C−H functionalization represents the most powerful platform that has emerged in the last years, empowering rapid synthesis of complex natural products and enabling diversification of bioactive scaffolds based on natural product architectures. In this review, we present an overview of the recent strategies towards the total synthesis of heterocyclic natural products enabled by C−H functionalization. Heterocycles represent the most common motifs in drug discovery and marketed drugs. The implementation of C−H functionalization of heterocycles enables novel tactics in the construction of core architectures, but also changes the logic design of retrosynthetic strategies and permits access to natural product scaffolds with novel and enhanced biological activities.     

Total Synthesis of the Natural Product-Pinosylvin and its Analog

Polyhydroxy stilbenes were proved to have many biological activitiesl'2. 'We havereported the total synthesis of tWo natural products-resveratrol (3,5,4'-tTihydroxylstilbene) and isorhapontigenin 3'4 which were first found in a traditional Chinese herb,G.Parvghlium by M. Lins et al. Herein,we want to present the total synthesis of anothernatural hydroxyl stilbene, pinosylvin (3,5-dihydroxy stilbene,10) isolated from this plantand its analog (3,5,3',5'-tetfahydroxy stilbene,9 ). In the synth…     

The First Total Synthesis of Five Elegan Type Natural Products

Eleganolone(1)['],eleganoloneaCetate(2)['],elegandiol(3)['],eleganonal(4)l']talepoxyeleganolone(5)[']arefiVeaCyclicditerPenesisolatedftomCystOseiraeIops,boiro,BghrcariabghrcataandCvstoseirabalearicaetc.(Ctall).Ckart1TherearempsuchlinearditerPenesorseSqultempshavebeenisolatedasnatUIprodUCtSsinceeleganlonewasfirStisolatednearly2oyearsago.AnditisnoteWrthythathesecompoundsexhibitsiedCallbiologicalactivities,suchasinhibihngthecontractileactivitiesOfaCetylchOline(Ach)andhi~neoos)onileummus…     

Synthesis and Properties of a Heteronuclear Ag(Ⅰ)/Ni(Ⅱ) Complex

A complex, Ni (en)2 Ag3 (CN) 5 (en = ethylenediamine), was obtained through the reaction of [Ag (CN) 2] -units with Ni Ⅱ -diamine cation [Ni (en)2] 2 , and the structure was determined by single crystal X-ray diffraction. It is indicated that the complex has a 3D architecture through the silver-silver interactions and the bridging cyano groups. This complex displays interesting luminescent properties caused by argentophilicity at room temperature in solid state.     

Syntheses of Iso-Condensed Heteroaromatic Pyrroles and the Application to the Total Synthese of Natural Products

A novel method, namely the intramolecular 1,3-dipolar cycloaddition and cycloreversion ofazido-alkylidene malonates, for the preparation of iso-condensed heteroaromatic pyrroles has beendeveloped. The application of this method for the synthesis of 2,4-dihydropyrrolo[3,4-b]indole ringsystem, as well as the application of this ring system for the total syntheses of ellipticine alkaloids arereported.     

Synthesis of Polymer-Bonded Carbonyl Ruthenium (Ⅱ) and Osmium (Ⅱ) Porphyrins

Studyonmetalloporphyrincomplexesusedasenzymemodelcatalyzingtheoxidationofalkaneandepoxidationofalkeneiscurrentlyaveryactiveresearchfieldl.ThereactivityofrutheniumporphyrincomplexeswasusedasoxidationcatalystsbecausetheirrelationstocytochromeP-450haveb...     

Synthesis and properties of the copper(Ⅱ) complexes with stable radical

Four novel copper(Ⅱ) complexes have been synthesized,namely Cu(hfac)2NITPhNO2 (1),Cu(hfac)2NITPhCH3 (2),Cu(pfpr)2NITPhNO2,(3) and Cu(Pfpr)2NITPhCH3 (4),where hfac= hexafluoro-acetylacetonate,pfpr=pentafluoropropionate,NITR.=2-R-4,4,5,5-tetraniethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide.(R=4-nitrophenyl,4-methylphenyl).These complexes were rharicter-ized by elemental analyses,IR,electronic spectra and molar conductance.The temperature-dependent magnetic susceptibility of complexes 1 and 3 have been studied in the 4 300 K range,giving I he exchange integral J=10.56 cm-1 for complex 1 and J =-30.9 cm-1 for complex 3.     

Synthesis and Crystal Structures of the α and β Forms of Bis(salicylaldoxime)copper(Ⅱ) Complexes

Modified α and β bis(salicylaldoxime)copper(Ⅱ) have been obtained by recrystallization from ethyl acetate(CCDC Nos. 212157 & 212158). The X-ray analysis reveals that the two modificated forms have the same structure with different geometric parameters. The α form crystallizes in the P2(1)/c space group and the β form in the P1 space group. Both the crystal structures consist of centrosymmetric monomeric molecules of Cu(OC6H4CNOH)2. The IR spectra are in agreement with the structural data.     

Synthesis and Properties of u-Oxamido Heterobinuclear Cu(Ⅱ)-Co(Ⅱ) Complexes

Three heterobinuclear complexes were synthesized, namely [Cu (oxpn) Co (L)2] (ClO4)2·xH2O(L= 2,2'-bipyridyl(bpy), 1,10-phenanthroline(phen) , and 5-nitro-1, 10-phenanthroline (NO2-phen)), where oxpn represents N, N'-bis(3-aminopropyl) oxam-ido. Based on 1R, elemental analysis, conductivity measurement and electronic spectra, these complexes were characterized by an extended oxamido-bridged structure with Cu(Ⅱ) in a planar environment and Co(Ⅱ) in a octahedral environment. The symmetry of the cation is very close to C2v.The complexes were also characterized with variable temperature (4~300K) magnetic susceptibility, and the data were fit for the susceptibility equation derived from spin Hamilton, H= -2JS1.S2-DSx12 by least square strategy. The exchange integral, J, was found to be -22.36 cm-1 (for bpy);-15.45 cm-1 (for phen); -19. 10cm-1(for NO2-phen), indicating that there is a weak antiferromagnetic spin-exchange interaction between the metal ions.     

Synthesis and Characterization of One-dimensional and Two-Dimensional Porphyrin Polymers (Ⅰ)

Porphyrin polymers are of interest in relation to conductive materials[1, 2], catalysts for photosynthetic charge separation[3], or the fundamental features in biological systems[4]. There have been many versatile studies about them[5.6]. The one-dimensional "Shish Kebab"porphyrin polymers synthesized with a new method different from those reported and Schiff-base porphyrin polymers with two-dimensional nano-structure have provided a new field of study. The present paper covers highly ordered…     

Synthesis and Characterization of Dipeptide Schiff Base Complexes of Copper(Ⅱ), Zinc(Ⅱ), Nickel(Ⅱ) and Cobalt(Ⅱ)

N-saliCylidenchnoacidcomplexesInayserveasmodelsfOrN-bodoXylidenedoacidcomp1exSystmschcharebelieVedtObetheintermediatesinthetranboIlationprocessl'l.ThecoordinaionOfametaJiontosuchSchiffbasesstabilizestheazomethine1inkag,underconditionsthatwouldothendsepromotebondcleaVag[2-5].Inaddition,thecomplexesOftalnoeddScAfbasesareconsideredtobeanewldndOfpoentialanhbactrialandanhcanceragentsl6].However,littleattentionhasbeengiventoSystemsinwhchtheScusbasesarederivedfromsimPlepePtides.ThispoprrePO…     

Synthesis and Crystal Structure of Trans-bis(acesulfamato-O)tetraaquazinc(Ⅱ)

<正>The title compound,trans-bis(acesulfamato-O)tetraaquazinc(Ⅱ)(I,C_8H_(16)N_2O_(12)S_2Zn), crystallizes in the triclinic system,space group P_1~-with a=5.1638(5),b=8.5338(9),c=9.9583(9) (?),a=74.325(8),β=81.112(7),γ=75.800(8)°,V=407.77(7)(?)~3,Z=1,F(000)=236,R_(int)=0.085, T=296 K,the final R=0.029 and wR=0.078 for 1832 observed reflections with I2σ(I).The Zn~Ⅱcentre resides on a centre of symmetry and has a distorted octahedral geometry.The basal plane is defined by two carbonyl O atoms of two monodentate trans-oriented acesulfamato ligands and two trans-aqua ligands.The axial positions in the octahedron are occupied by two trans-aqua ligands. Intermolecular O-H…O hydrogen bonds produce R_2~2(8)and R_2~2(16)rings,which lead to two-dimensional polymeric chains.     

η6-Arenetricarbonylchromium(0) Complexes in the Synthesis of 1,4-Benzodiazepines and Its Nucleophilic Substituted Products

Abstract

7-Chloro-5-carbomethoxy-1,3-dihydro-2H-1,4-benzodiazepines and its nucleophilic substituted products were synthesized via η⁶-arenetricarbonylchromium(0) intermediates. Ring enlargement of 5-chloro-N-chloroacetylisatin with hexamine in presence of Cr(CO)₆ led to the formation of 7-chloro-5-carbomethoxy-1,3-dihydro-2H-1,4-benzodiazepine in good yield with reduced reaction time. Nucleophilic substitutions on arene ring of η⁶-arenetricarbonylchromium(0) complexes with thiols, phenol, and primary amines were successfully carried out in decalin medium.     

Synthesis and Crystal Structure of Cobalt(Ⅱ) and Copper(Ⅱ) Complexes Involving L-Aamino Alcohols

Two novel L-amino alcohol coordination cobalt and copper complexes I and Ⅱ were obtained separately from the direct reaction of L-plenylglycinol with Co(Ⅱ) acetate tetrahydrate in anhydrous ethanol and L-leucinol with Cu(Ⅱ) chloride dihydrate in anhydrous methanol. The structures of I and Ⅱ were determined by single-crystal X-ray diffraction and further characterized by elemental analysis and IR. For I: [Co3(C51H66N3O16)]2(OAc), monoclinic, space group P21, a = 15.022(3), b = 14.242(3), c = 28.922(6) , β = 98.944(4)o, V = 6112(2) 3, Z = 4, Dc = 1.339 g/cm3, the final R = 0.0860 for 21906 observed reflections with I 2(I). For Ⅱ: Cu2[C24H58N4O7Cl]Cl, orthorhombic, space group P212121, a = 6.1861(13), b = 20.838(4), c = 28.274(6) , V = 3644.6(13) 3, Z = 4, Dc = 1.310 g/cm3, the final R = 0.0642 for 11106 observed reflections with I 2(I). The complexes were then used to catalyze the Henry reaction and catalytic activity determined by 1H NMR.     

Synthesis and Magnetic Studies of Oxamido-Bridged Cu(Ⅱ)-Fe(Ⅱ) Heterobinuclear Complexes

~The~andmagneti~Of~~areatoPicthahasndchinndinndnd.bondinthewiin-wtofbinudearCU(n)-Fe(u)-,chewedwiththe~alleq-nettrioftwnew~-,[CU(oxa)Fe(L)21sa(Lbo1,1o-~(Phen)nd5-nithe1'1o-~(NQ-Phen)),whereOxaisN,N'-bis(2-amhathy).edfor.-Synboor(1)ToCh(oxae)2(94.2mp'o.4ed)theindri(5nd)wasbo-lyadtalaedboofso.Wio(111.2mp,o.4nuno)inmeto(1ond)ndaboofPhen(144-2mp,o.8mrnO)inrne~(1OrnL)underN2atrmpe.theedfor2hthegreddebm~thuSfo~wereforoff,washededtimeswithrne~anddiethyletheranddriedoverP2QUnderededpe.ha:C,…     

Study on the Synthesis and Characterization of Novel Immobilized β-Cyclodextrin Polymer (Ⅰ)

A series of novel β-cyclodextrin polymers was synthesized by immobilization of β-cyclodextrin on the chloromethylated crosslinked polystyrene carriers. The synthetic conditions such as reaction time, temperature, molar feeding ratio of reactants, the degree of crosslinking of polystyrene and the catalysts used were studied in detail and the chemical and physical structures of the formed β-CDpolymers were characterized. Results show that the preparation method is simple and the amount of β-CD immobilized is high. As biomedical adsorbents, they were tested for removal of various endogenous and exogenous toxins such as phenols, aromatic amins, barbitals and unconjugated bilirubin. Results indicate that the adsorptión capacity for those toxins can be enhanced by the inclusion interaction among the β-CD, the substrate molecules and the β-CD polymers.