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1.
Motohiro Sonoda 《Tetrahedron》2008,64(50):11490-11494
A butadiyne-bridged square-shaped pyridinophane 2b having ester groups derived from triethylene glycol monomethyl ether was prepared and its self-assembling properties were investigated to assess the repulsive dipole-dipole interaction in less polar solvent and solvophobic driving force in polar solvents. Concentration-dependent 1H NMR spectra showed that whereas 2b did not self-assemble in chloroform-d, it did in polar solvents consisting of chloroform-d and methanol-d4 (4:6 to 6:4) with increasing association constants with the increasing methanol-d4 composition. Comparison of the free energies of association with those of the previously reported benzene macrocycle 1b indicates that solvophobically induced self-association of 2b is more promoted than 1b. The reasons for this difference are discussed from both enthalpy and entropy points of view. 相似文献
2.
Novel acyclonucleosides (9a-d, 10a-d, 18a,b and 19a,b) have been prepared using Pd(0) and cross-metathesis methodologies. The allylic N-alkylation under Tsuji-Trost conditions was used to introduce the nucleobase, while the Suzuki-Miyaura reaction afforded C-5 substituted uracil analogues. The cross-metathesis performed with a ruthenium catalyst was used to provide new acycloalkenyl nucleosides. The antiviral activities of all final compounds have been evaluated. 相似文献
3.
Synthesis of fluorine containing glycolurils and oxazolines from oxides of internal perfluoroolefins
Lyudmila V. Saloutina Aleksandr Ya. Zapevalov Victor I. Saloutin Pavel A. Slepukhin Mikhail I. Kodess Oleg N. Chupakhin 《Journal of fluorine chemistry》2009,130(10):853-860
The reaction of oxides of internal perfluoroolefins 1-3 with urea gave two kinds of novel fluorine containing N-heterocyclic compounds depending on the solvent nature: 1,5-bis(perfluoroalkyl)tetraazabicyclo[3.3.0]octane-3,7-diones 4a-c and 2-amino-5-fluoro-4,5-bis(perfluoroalkyl)-4,5-dihydrooxazol-4-ols 7a-d. Use of polar dimethylsulfoxide, N,N-dimethylacetamide and acetonitrile afforded glycolurils 4a-c in moderate yields. In dioxane, unexpected cyclization occurred resulting in oxazolines 7a-d in high yields. A similar reaction of oxiranes 2, 3 with urea in aqueous dioxane gave mixtures of 4,5-dihydroxy-4,5-bis(perfluoroalkyl)imidazolidine-2-ones 9b, c, glycolurils 4b, c and oxazolines 7b-d. The molecular structure of trans-isomers of oxazoline 7b and imidazolidine 9b has been established by X-ray crystallography. 相似文献
4.
Six new compounds, two cyclohexenones, named xylariacyclones A (1) and B (2), three cyclohexenone–sordaricin derivatives, named xylarinonericins A–C (3–5), and one amide derivative, named xylariamide (6), together with 11 known compounds were isolated from the broth extract of the endophytic fungus Xylaria plebeja PSU-G30. The structures were elucidated by analyses of NMR spectroscopic data and chemical methods. Compounds 3–5 are novel and unusual sodaricin derivatives with an ester moiety at C-6 of the sordaricin skeleton. In addition, compound 5 has a unique feature with an ester unit instead of an ether group at C-19. They were evaluated for antifungal activity against Candida albicans ATCC90028 and Cryptococcus neoformans ATCC90113. 相似文献
5.
Ashraf A Abbas 《Tetrahedron》2004,60(7):1541-1548
The 13-hydroxy macrocycles 7a-d were prepared in 40-50% yields by the condensation of 1,ω-bis(4-amino-1,2,4-triazol-3-ylsulfany)alkanes 2a-d with 1,3-bis(2-formyphenoxy)-2-propanol (9). Acylation of 7a-d with 2-chloroacetylchloride gave the corresponding esters 11a,b. Amination of 11a,b with different amines in acetone furnished exclusively the target lariat macrocycles 12a,b and 13 in 60-70% yields. Reaction of 2 equiv. of the macrocycles 11a,b with 1 equiv. of piperazine afforded the novel bis macrocyles 14a,b in 50-60% yields. Reduction of 7a-d with NaBH4 afforded the corresponding 13-hydroxyazathia crown ethers 15a-d in 65-70% yields. 相似文献
6.
Chemoselective photorearrangements of symmetrically substituted pyrazinobarrelene 4, quinoxalinobarrelene 5, and benzoquinoxalinobarrelenes 6 and 7 containing polar and non-polar groups under various conditions are described. In both direct and sensitized irradiation conditions, barrelenes 4-7 afforded similar bridging modes and photoproduct distributions suggesting a resemblance in the multiplicities of photoreactants upon excitation. Irradiation of pyrazinobarrelene 4a furnished almost equal amounts of photoproducts derived from DPM (vinyl-vinyl bridging) and ADPM (aryl-vinyl bridging) pathways. Pyrazinobarrelenes 4b-d underwent chemoselective rearrangements via the ADPM route. In the case of quinoxalinobarrelenes 5a-c and benzoquinoxalinobarrelenes 6b,c, vinyl-vinyl bridging was strongly favored. Benzoquinoxalinobarrelene 6a was insensitive to photochemical reactions. Heteroaryl-vinyl bonding was the preferred primary interaction in benzoquinoxalinobarrelene 7a whereas 7b favored the DPM route via vinyl-vinyl bridging. The photochemical behavior of the title compounds was explained in terms of energy minimization of the perturbed triplet state and diradical stabilization by polar and non-polar substituents. Plausible mechanisms for the photochemical reactions are also described. 相似文献
7.
Hideki Miyauchi Toshiaki Shimazaki Teruo Shinmyozu Kenichi Somekawa 《Tetrahedron》2008,64(18):4108-4116
Sensitized photocycloaddition reactions of 6,6′-dimethyl-4,4′-[1,3-bis(methylenoxy)phenylene]-di-2-pyrone (1) with electron-poor α,ω-diolefins such as ethylene diacrylate (2a) and polyoxyethylene dimethacrylates (2b-d) afforded site- and stereoselective macrocyclic dioxatetralactones (3a-d) and (4b) having 18- to 25-membered rings across the C5-C6 and C5′-C6′ double bonds, or C5-C6 and C3′-C4′ double bonds in 1, respectively. Similar photoreactions of 1 with electron-rich α,ω-diolefins such as poly(ethylene glycol)divinyl ether (2e and 2f) afforded crown ether-type macrocyclic compounds (5e and 5f) having 18- and 21-membered rings across the C3-C4 and C3′-C4′ double bonds in 1, respectively. The stereochemical features of 3b, 5e-xx, and 5e-nn were determined by the X-ray crystal analysis. The reaction mechanism was inferred by MO methods. 相似文献
8.
Shunpei Nobusue Ayumi Yoshizaki Masahito MikiHirokazu Miyoshi Akihiro Shimizu Yoshito Tobe 《Tetrahedron》2014
A nucleophile-induced cyclization of octadehydrodibenzo[12]annulene derivative 1b was investigated. Treatment of 1b with BuLi gave fused 5–9-membered ring products, dibenzobicyclo[7.3.0]tetraenediynes 2a and 2b, formed via a single transannular cyclization reaction. The reason why double cyclization did not occur is ascribed to the structure of a plausible anionic intermediate in which a negative charge locates apart from the remaining triple bond carbons. The second cyclization did not take place even when once-isolated product 2b was treated with BuLi because of the higher reactivity toward a nucleophile of the fulvene moiety compared to the triple bonds. On the other hand, heating a chlorobenzene solution of 2b containing cyclohexa-1,4-diene gave products 3a–c possessing a benzonaphthopentalene framework via a Bergman cyclization pathway albeit in low yields after inter- or intramolecular hydrogen abstraction. Moreover, iodine-induced transannular cyclization of 2b afforded the corresponding diiodide 3d. 相似文献
9.
Tetsuya Takeya Hirohisa Doi Tokutaro Ogata Tsuyoshi Otsuka Iwao Okamoto Eiichi Kotani 《Tetrahedron》2004,60(30):6295-6310
A simple method for the direct synthesis of 2,2′-binaphthols 2 and dinaphtho[1,2-b;2′,1′-d]furans 3 under mild conditions was developed, utilizing a biaryl coupling reaction via electron donor-acceptor complexes of 1-naphthols with SnCl4. Heating of the complex in a sealed tube for (18-24 h) afforded the corresponding o-o coupled product 2 in excellent yield. Prolonged reaction (56-65 h) under the same conditions afforded 3 in high yield in one step. We also found that in the case of α-naphthol without substituents other than a hydroxyl group at the C-1 position, regioselective o-o coupling reaction proceeded. The products 2a, 2b and 2g should be useful as synthetic intermediates for naturally occurring 3,3′-bijuglone, 3,3′-biplumbagin and elliptinone. 相似文献
10.
Bin Tu 《Tetrahedron》2004,60(41):9017-9029
New bilirubin congeners (1a-1d) with the central C(10) CH2 replaced by C(CH3)2 were smoothly synthesized by coupling two identical dipyrrinones with 2,2-dimethoxypropane under acid catalysis. The new yellow pigments, with acid chains varying from acetic (n=1) to propionic (n=2) to butyric (n=3) to hexanoic (n=5), exhibit unusual amphiphilicity relative to the parent mesobilirubins without the gem-dimethyls and have highly favorable solubility in organic solvents ranging from nonpolar (benzene) to polar (CH3OH). Like the parent rubins, 1a-1d can easily bend about the middle but unlike the parents they cannot form mesobiliverdin analogs. NMR spectroscopic analysis and molecular dynamics calculations indicate that, like the parents, 1a-1d adopt ridge-tile shapes that are stabilized by intramolecular hydrogen bonding. Confirmation of the conformation in 1b comes from its X-ray crystallographic structure. 相似文献
11.
Philip J. Burke William Clegg Terence C. Jenkins Ian T. Meikle 《Tetrahedron letters》2010,51(30):3918-7450
Treatment of the N-nitroaryl-3-hydroxypiperidine derivatives 12 and 13 with thionyl chloride afforded the corresponding N-aryl-2-chloromethylpyrrolidines 5 and 15 via a ring-contraction process involving an intermediate aziridinium ion. 相似文献
12.
Amidrazone 1a and the tricarbonyl derivatives 2b-d reacted in boiling ethanol in the presence of 2,5-norbornadiene 5 giving the pyridine derivatives 6b-d respectively (59-72%) and in the presence of 2,3-dihydrofuran 7 yielding the lactones 10b-d (39-44%). The 2,2′-bipyridine derivatives 6e-g were similarly obtained in good yield (81-87%) from the reaction of amidrazone 1b and tricarbonyl derivatives 2b-d in the presence of 2,5-norbornadiene 5. 相似文献
13.
Antonino Corsaro Ugo Chiacchio Venerando Pistarà Roberto Romeo Felicia D'Andrea Emanuele Attolino 《Tetrahedron》2004,60(17):3787-3795
Completely protected 4-deoxy-α-L-threo-hex-4-enopyranosides 1c,d undergo the dichlorocarbene addition affording exclusively diastereomeric adducts 5c,d with the cyclopropane ring anti to the C-3 alkyloxy substituent, while the reaction with 3-unprotected derivatives 1a,b affords a mixture of syn and anti derivatives. Under the Simmons-Smith cyclopropanation adducts 2a-d with a syn stereochemistry are obtained. Starting from 5b, the cyclopropanated sugar 3b is obtained by reduction with LiAlH4, thus the two diastereomers 2b and 3b can be stereoselectively obtained through the two different pathways. For a useful comparison, 4-deoxy-β-L-threo-hex-4-enopyranoside 1e was also subjected to the above two cyclopropanation methods affording the expected cycloadduct 2e and a diastereomeric mixture of dichlorocycloadducts 4e and 5e (4e/5e=2.8:1). 相似文献
14.
Gannerla Saidachary Kasagani Veera PrasadMudulkar Sairam Bhimapaka China Raju 《Tetrahedron letters》2014
A facile method has been developed for the synthesis of 4H-chromene-3-carboxylates 3a–d by the nucleophilic substitution reaction of 2-hydroxy-2H-chromene-3-carboxylates 2a–d with triethylsilane in the presence of BF3·O(C2H5)2. Cyclocondensation of 4H-chromene-3-carboxylates 3a–d with benzylamines 4a–d afforded a series of 2,3-dihydrochromenopyrrolones 5a–p and with propargylamine afforded 2-propynyl-2,3-dihydrochromenopyrrolones 6a–d. Click reaction of 6a–d with benzyl azides 7a–d provided a series of 1H-1,2,3-triazolylmethyl-2,3-dihydrochromenopyrrolones 8a–p. Thus synthesized compounds 3a–d, 5a–p, 6a–d, and 8a–p are novel heterocyclic compounds and being reported for the first time. 相似文献
15.
Takayuki Doi 《Tetrahedron letters》2004,45(29):5723-5726
Various trialkylsilyl linked polymer supports have been prepared by reacting benzyl chloride resin and a di-Grignard reagent with CuBr·Me2S, followed by dialkylchlorosilanes. 4-Alkoxybenzyl type resin, Wang-Cl 2c and Argogel Wang-Cl 2d provided 4c and 4d at ambient temperature, whereas nonactivated resin, Merrifield 2a and Argogel-Cl 2b afforded 4a and 4b at 60 °C. Primary and secondary alcohols 6-10 were attached to the alkyldiisopropyl-linked Wang type resin 4cA by a novel dehydrosilation with B(C6F5)3 as well as by conventional methods. 相似文献
16.
Hikaru HasegawaHisanori Senboku Yoshinori KajizukaKazuhiko Orito Masao Tokuda 《Tetrahedron》2003,59(6):827-832
Tandem cyclization of N-propargylaminyl radicals, generated by N-chlorination of (E)-alk-4-enylamines 2a-d and 2f followed by treatment with tributyltin radical, afforded 2-methylenepyrrolizidines 3a-d and 3f in a highly stereoselective manner. A similar radical cyclization of (Z)-N-propargyl-1-methyl-5-phenylpent-4-enylamine (2e) gave pyrrolizidine 3b having the same stereochemistry as that obtained from the E isomer 2b. 相似文献
17.
Tetsuro Shimo 《Tetrahedron》2005,61(33):8059-8064
Solid-state photosensitized reactions of 4-acyloxy-2-pyrones (1b,c) with maleimide (2) afforded endo-endo double-[4+2] cycloadducts (3b,c) with high stereoselectivity. Sensitized photoreactions of 1a-d with 2 in solution gave exo-endo double-[4+2] cycloadducts (4a-d). 2-Pyrones 1a-d were photolyzed to give carboxylic acids (5a-d) via their valence isomerization in the solid state and in solution. Such kinds of photoreaction of the 4-acyloxy-2-pyrones were dramatically different from regio- and stereoselective [2+2] cycloadditions of 4-alkyloxy-2-pyrones. The photoreaction mechanisms of 1 with 2 and 1 itself were analyzed by powder X-ray diffraction analysis and MO calculations. 相似文献
18.
Palladium catalyzed cross-coupling of 3-amino- and 3-acylamido-2-bromopyridines 1a-f with triethyl phosphite allowed the synthesis of 3-amino- and 3-acylamido pyridine-2-phosphonic acid diethyl esters 2a-f, whereas nickel catalysts, although providing access to related anilido-2-phosphonates, proved inactive. Reduction of the aminophosphonate 2a with LiAlH4 afforded 3-amino-2-phosphinopyridine (3a), which was cyclocondensed with dimethylformamide dimethyl acetal (DMFA) via phosphaalkene intermediates 4a to the novel pyrido[b]-anellated 1,3-azaphosphole 5a. Reaction of amidophosphonates 2b-f with LiAlH4 did not result in the expected reductive cyclization, as shown by closely related anilido-2-phosphonates, but led to product mixtures containing N-secondary 3-amino-2-phosphinopyridines 3b-f as the main or major component. The conversion of 3b,d,e with DMFA to 5b,d,e provides first examples of N-substituted pyrido[b]-anellated azaphospholes. Structures were confirmed by multinuclear NMR and X-ray crystallography (for 2c, 3b). 相似文献
19.
Zainab Al Shuhaib Deiniol H. Davies Mark Dennis Daniel M. Evans Matthew D. Fletcher Herjan Franken Paul Hancock Jackie Hollinshead Iestyn Jones Kristina Kähm Patrick J. Murphy Robert Nash David Potter Richard Rowles 《Tetrahedron》2014
The cyclisation of mono-protected and bis-protected guanidines 8a–j under standard iodocyclisation conditions (I2/K2CO3) gave the guanidine heterocycles 9–25 via either a direct cyclisation or by a cyclisation/ring-contraction process, which could be controlled by careful selection of conditions. 相似文献
20.
Guillaume Carel Alina Saponar Nathalie Saffon Marc Vedrenne Stéphane Massou Gabriela Nemes Ghassoub Rima David Madec Annie Castel 《Tetrahedron》2014
New oxathioethers macrocycles have been synthesized and characterized. Each macrocycle consists in structurally defined ether and thioether moieties and an exocyclic double-bond (2a–c) or a hydroxymethyl group (3a–c). Macrocycles (2a–c) have been synthesized by reaction of dianions of thioethers diols (1a–c) with 3-chloro-2-chloromethylprop-1-ene. Their hydroboration/oxidation led to corresponding primary alcohols (3a–c). Structures of compounds (2b) and (3a) have been determined by X-ray diffraction. The reactivity of the hydroxyl group allowed the preparation of oxathioethers macrocycles bearing a polyether chain or a benzyl group (4a,b) and the synthesis of new bicyclic sandwich-type compounds (5a,b). The ability of these functionalized macrocycles to coordinate to palladium has been investigated. 相似文献