A New Bibenzyl Derivative from Dendrobium moniliforme

A new bibenzyl derivative,3,4-dihydroxy-4′,5-dimethoxy bibenzyl,was isolated from a orchid Dendrobium moniliforme. The structure elucidation and ^1H,^13C NMR assignments were achieved by spectroscopic method.     

3-(3＇-乙酰基-5＇-芳基-1＇,3＇,4＇-二氢噁二唑-2＇-)色酮的微波促进合成

将微波应用于促进有机合成是近年来兴起的新技术,已受到极大注意,我们采用简单的微波反应装置,成功地合成了3－杂环基取代的色酮,杂环基取代的色酮因其显著的生理活性,而成为近年来的研究特点,以3－甲酰基色酮为原料,与芳酰肼反应得到相应的芳酰腙,再用乙酸酐关环,合成了一系列3位为1,3,4－二氢恶二唑基取代的色酮（3）,为在合适的母体上引入杂环提供了一系新思路,合成路线如下。     

A Novel Fused Phosphorus Heterocycle：4—（1′，2′,3′,4′—Tetrahydro—1,3,2—benzodiaaphosphorin—2′—sulfide）—3,4b,4a—thiazphosphaphenanthridine Derivative

The first example of fused phosphorus heterocyclic 4-[1′-(β-bromoethyl)-4′-oxo-3′-propyl-1′,2′,3′,4′-tetrahydro-1,3,2-benzodiazaphosphorin-2′-sulfide]-1,2,3,4,4a,4b,5,6-octahydro-6-oxo-5-propyl-3,4b,4a-thiazphosphaphenanthridine 4a,2′-dioxide was synthesized in excellent yield by refluxing a mixture of 1-(2-bromoethyl)-2,3-dihydro-3-propyl-1,3,2-benzodiazaphos phorin-4(1H)-one 2-oxide with carbon disulfide in benzene in the presence of triethylamine.     

A Practical Synthesis of （S）—（＋）—2—（6′—methoxyl—2—naphthyl） propionic Acid

A simplified procedure for enantioselective synthesis of (S)-( )-2-(6′-methoxyl-2-naphthyl)propionic acid ((S)-( )-naproxen), starting from (6-methoxy-α-naphthyl)-1-propanone,with D-mannitol as auxiliary catalyzed by SmCl3 in one-pot is described. The yield is 87.5%(ee value 99%).     

A Convenient Synthesis of 6,8-Dimethoxy-3-[（2-（4-methoxyphenyl）ethyl）isocoumarin

6,8-Dimethoxy-3-[2-（4-methoxyphenyl）ethyl]isocoumarin was synthesized by condensation of 5,7-dimethoxyhompophthalic acid with 3-（4-methoxyphenyl）propanoyl chloride. The structure of the synthesized compound was confirmed by its mass spectrometric studies. The synthesized compound serves as a model for synthesis of DL-agrimonolide.     

Synthesis and Crystal Structure of (Z)-Ethyl-4-(4-methoxy)benzylidene-2-(3,5-dimethoxypheny-tetrahydrofuran-3,3-dicarboxylate

The title compound (Z)-ethyl-4-(4-methoxy)benzylidene-2-(3,5-dimethoxyphenyl)- tetrahydrofuran-3,3-dicarboxylate has been synthesized, and its crystal structure was characterized by X-ray single-crystal diffraction. The crystal belongs to triclinic, space group P1-, with a = 8.140(3), b = 11.966(4), c = 13.771(5) α = 67.366(4), β = 85.165(5), γ = 75.806(4)°, V = 1200.1(7) 3, Z = 2, C26H30O8, Mr = 470.50, Dc = 1.302 g/cm3, F(000) = 500, λ(MoKα) = 0.71073 , μ = 0.096 mm–1, R = 0.0659 and wR = 0.1841 for 3080 observed reflections (I > 2σ(I)). As a key intermediate of HIV-1 integrase inhibitor, the synthesis and structure confirmation of the title compound are important for further studies.     

Synthesis of 6（E）—Geranylgeraniol—19—oic Acid

Facile synthesis of 6(E)-geranylgeraniol-19-oic acid 1,a naturally occurring alicyclic diterpene acid, by a Horner-Wadsworth-Emmons olefination of two readily available fragments 2 and 3,is described.     

A Novel Asymmetric Synthesis of （-）-cis-1, 3-Dibenzylhexahydrofuro[3, 4-d]imidazole-2,4-dione

(-)-cis-1, 3-Dibenzyl-hexahydrofuro[3, 4-d]imidazole-2, 4-dione was prepared by a new synthesis method from meso dicarboxylic acid and dehydroabietylamine by asymmetric reduction in good yield with up to 91.6% e.e. value.     

Synthesis and Crystal Structure of 2,5—Bis（morpholino）—3,4—bis（p—chlorophenyl）thiophene

1 INTRODUCTION -Thiocarbonylthioformamide synthesized in 1980[1, 2] is a class of stable and almost unexplored compounds[3]. We have reported the reaction of - thiocarbonylthioformamides in our previous paper[4]. Here, we will report a novel synthesis of 2 by the reaction of 1 and trimethyl phosphite in refluxing xylene. In order to determine the structure of 2, X- ray crystallographic study was carried out. 2 EXPERIMENTAL 2. 1 Preparation of the title compound Trimethyl phosph…     

Application of DEPBT on the Synthesis of the Protected Dipeptides Containing Histidine with Unprotected Imidazole Group by Solution Method

3- (Diethoxyphosphoryloxy)- 1,2,3-benzotriazln-4 (3H)-one (DE-PBT) was an organophosphorus coupling reagent developed by our group. It was an effective coupling reagent for the synthesis of protected peptides containing Tyr, Ser and Thr with unprotected hydroxy group on their side chain. The further study of the synthesis of a series of protected dipeptides containing hisfidine with unprotected imidazole group using DEPBT is reported. During the synthetic procedure, the imidazole group of histidine did not need to be protected. When the carboxyl components were N-protected aromatic amino acids or basic amino acids, the yields were relatively high (63%--81%). However,when the carboxyl components were N-protected acidic amino acids, the yields were relatively low (47%--48%). The results expanded the application of DEPBT on the synthesis of bioactive peptides containing histidine.     

Stiff‐Stilbene Photoswitches: From Fundamental Studies to Emergent Applications

Stiff‐stilbene, a sterically restricted fused ring analogue of stilbene, has been regularly used as a model compound in theoretical studies of stilbene photoisomerization. Lately, owing to its excellent photoswitching properties, it is increasingly being applied to reversibly control the properties and function of chemical as well as biological systems. Stiff‐stilbene photoswitches possess a number of advantageous properties including a high quantum yield for photoisomerization and a high thermal stability. Furthermore, they undergo a large geometrical change upon isomerization and their synthesis is straightforward. Herein, we provide an overview of the basic properties of stiff‐stilbene and of recent applications in supramolecular chemistry, catalysis, and biological systems.     

Homo- and hetero-[3]rotaxanes with two pi-systems clasped in a single macrocycle

Here we present the first synthesis of a [3]rotaxane with two dumbbell components threaded through a single gamma-cyclodextrin macrocycle. This synthesis is carried out in two steps: first one dumbbell is synthesized threaded through the macrocycle to give a [2]rotaxane, then a second dumbbell is synthesized through the remaining cavity of the [2]rotaxane. We have synthesized a hetero- [3]rotaxane with one stilbene and one cyanine dye threaded through gamma-cyclodextrin, which exhibits quantitative energy transfer between the two encapsulated dyes. The stilbene [2]rotaxane intermediate in this synthesis has a remarkably high affinity for suitably shaped hydrophobic guests in aqueous solution, facilitating the synthesis of [3]rotaxanes and suggesting possible applications in sensors.     

Synthesis of p-Nitro-stilbene Derivatives with Different Linking Bonds:An Attempt to Tune Spectroscopy of Dyes with Molecular Engineering

The synthesis, characterization and spectroscopy of a range of novel substituted p‐nitro‐stilbene derivatives with different bridging bonds were presented. The molecular structure characterization was carried out with ¹H NMR, ¹³C NMR and elemental analysis. The ultraviolet/visible spectroscopy and photoluminescence of the compounds were investigated in various solvents. The maximal absorption wavelength of the nitro‐stilbene derivatives with an ether bond exhibited approximate 30 to 40 nm bathochromic shift compared to that of nitro‐stilbene dyes with an ester bond. Furthermore, the nitro‐stilbene derivatives with an ether bond displayed obvious photoluminescence, while the nitro‐stilbene derivatives with an ester bond showed weak fluorescence emission. The detection of the cyclic voltammograms of the nitro‐stilbene derivatives showed that the nitro‐stilbene compounds with different linking bonds exhibited different redox proceses at various scan rates. The theroretical calculations of HOMO and LUMO energy of nitro‐stilbene derivatives showed that the energy gaps between HOMO and LUMO of 3 and 4 were lower than those of 1 and 2 . The electron density of the frontier orbitals of nitro‐stilbene derivatives was observed to be affacted by the linking bonds, which thus made it possible to tune the spectroscopy of these dyes with chemical strategy. The differential scanning calorimetry and thermogravimetry showed that the thermal stabilities of these dyes were not much affected by the linking bond. The results presented in this paper would be great interest in development of ideal nitro‐stilbene derivatives for special purposes.     

Synthesis, dual fluorescence, and fluoroionophoric behavior of dipyridylaminomethylstilbenes

The synthesis, dual fluorescence, and fluoroionophoric behavior of two donor-sigma spacer-acceptor (D-s-A) compounds, trans-4-(N,N-bis(2-pyridyl)amino)methylstilbene (1H) and trans-4-(N,N-bis(2-pyridyl)amino)methyl-4'-cyanostilbene (1CN), are reported and compared to that of trans-4-(N,N-bis(2-pyridyl)amino)methyl-4'-(N,N-dimethylamino)stilbene (1DPA). To gain insights into the dual fluorescence properties for 1H and 1CN in polar but not in nonpolar solvents, model compounds resulting from a replacement of the stilbene group by alkyl (2R) or xylyl (2X) groups or from a replacement of the dipyridylamino (dpa) group by dianisoleamino (3AA), diethylamino (3EE), methylanilino (3MP), or diphenylamino (3PP) groups also have been investigated. In addition to 1H and 1CN, all four compounds of 3 display dual fluorescence. The locally excited (LE) fluorescence mainly results from the stilbene group and the ICT fluorescence from the through-bond interactions between the amino donor and the stilbene acceptors. In the presence of transition metal ions such as Zn(II), Ni(II), Cu(II), and Cd(II), the ICT processes are switched from dpa (D) --> stilbene (A) in 1H and 1CN to stilbene (D) --> dpa/metal ion (A) in their complexes. Whereas the ICT states for the complexes are generally nonfluorescent, an exception was found for the case of 1H/Zn(II). As a result, substituent-dependent fluoroionophoric behavior has been demonstrated by 1H, 1CN, and 1DPA in response to Zn(II).     

Synthesis and photochemistry of novel bromo substituted stilbene derivatives as triplet state sensitizers for the generation of singlet oxygen

We have presented the synthesis and characterization of three new bromo substituted stilbene derivatives,p-3,4,5-trimethoxy-p'- 2,3,4,5,6-pentabromostilbene(C1),p-N,N-dimethylamino-p'-2,3,4,5,6-pentabromostilbene(C2) and p-N,N-diphenylamino-p'- 2,3,4,5,6-pentabromostilbene(C3) in this letter.The UV/vis absorption and photoluminescence were investigated in various solvents.The maximal absorption wavelength of C1 exhibited blue-shift to those of C2 and C3 in different solvents.No florescence emission could...     

Synthesis of cicerfuran, an antifungal benzofuran, and some related analogues

Routes were investigated for the synthesis of cicerfuran, a hydroxylated benzofuran from wild chickpea implicated in resistance to Fusarium wilt, and some of its analogues. A novel method is described for the synthesis of oxygenated benzofurans by epoxidation and cyclisation of 2′-hydroxystilbenes. The stilbene intermediates required could be synthesised by palladium-catalysed coupling of styrenes with mono-oxygenated aryl halides but not with di-oxygenated aryl halides. Stilbenes corresponding to the latter were synthesised by Wittig reactions.     

Stiff-Stilbene Photoswitches: From Fundamental Studies to Emergent Applications

Stiff-stilbene, a sterically restricted fused ring analogue of stilbene, has been regularly used as a model compound in theoretical studies of stilbene photoisomerization. Lately, owing to its excellent photoswitching properties, it is increasingly being applied to reversibly control the properties and function of chemical as well as biological systems. Stiff-stilbene photoswitches possess a number of advantageous properties including a high quantum yield for photoisomerization and a high thermal stability. Furthermore, they undergo a large geometrical change upon isomerization and their synthesis is straightforward. Herein, we provide an overview of the basic properties of stiff-stilbene and of recent applications in supramolecular chemistry, catalysis, and biological systems.     

Total Synthesis of (+)‐Machaeriols B and C and of Their Enantiomers with a Cannabinoid Structure

An efficient and concise synthesis of the biologically interesting (+)‐machaeriol B ( 2 ) and its enantiomer 5 was accomplished from O‐phenylhydroxylamine ( 7 ) in four steps (Scheme 2). In addition, the first total synthesis of natural (+)‐machaeriol C ( 3 ) and its enantiomer 6 was achieved from the readily available ester 15 in eight steps (Scheme 4). The key strategies in the syntheses of 2 and 5 involved benzofuran formation through a [3,3]‐sigmatropic rearrangement and trans‐hexahydrodibenzopyran formation by a domino aldol‐type/hetero‐Diels–Alder reaction. In the case of 3 and 6 , the key steps were stilbene formation by a Horner–Wadsworth–Emmons reaction and trans‐hexahydrodibenzopyran formation by domino reactions.     

Theoretical calculations of the structure of a donor—acceptor stilbene, azobenzene and related molecules

The structures of a substituted stilbene, azobenzene, and two isomeric benzylidene anilines containing the 4-dimethyl-amino group at one end of the molecule and the 4′-nitro group at the other, have been calculated using the semiempirical MNDO, AM1, and PM3 methods and the ab initio HF/3-21G method. The results are compared with experimental data where available. The MNDO method gives a very poor account of the geometry of the stilbene, but both the AM1 and PM3 methods correctly predict the planarity of the substituted stilbene and nitrobenzylidene aniline but erroneously predict a non-planar structure for the azobenzene. In contrast, the ab initio method predicts planar structures for the substituted stilbene, azobenzene, and nitrobenzylidene aniline, and a twisted structure for the isomeric benzylidene nitroaniline, in line with crystallographic data. This loss of planarity for the benzylidene nitroaniline is almost certainly responsible for its smaller non-linear activity and for the hypsochromic shift observed in its low energy absorption band relative to the other molecules.     

Protective Effects of Resveratrol and its Analogues against Free Radical-Induced Oxidative Hemolysis of Red Blood Cells

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