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1.
Takahito Itoh Masato Miyachi Masataka Kubo 《Journal of polymer science. Part A, Polymer chemistry》1999,37(9):1285-1292
2,5‐Bis(dicyanomethylene)‐2,5‐dihydrofuran (TCNF) is not homopolymerizable with any initiators, but copolymerizable with styrene (St) in an alternating fashion. Reactivity of TCNF was compared with that of 2,5‐bis(dicyanomethylene)‐2,5‐dihydrothiophene (TCNT) on the basis of the terpolymerization of the TCNT‐TCNF‐St system and the rates of addition reactions of AIBN with TCNT and with TCNF. TCNF was found to be lower in reactivity than TCNT. The relative reactivity was explained with the energy difference between quinonoid structure and benzenoid one. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1285–1292, 1999 相似文献
2.
2,5-Dimethylene-2,5-dihydrofuran (3), generated flash pyrolitically, underwent di- and trimerization reactions to give cyclic dimer and trimer. Compound 3 was trapped with methanol, ethanol, bromine, acetic acid, thiophenol and oxygen. Results from trapping experiments suggest that the diradical form of 3 is involved. 相似文献
3.
2,5-Dimethoxy-2,5-dihydrofuran (DDF) reacts with dichloroketene to give 7,9-dimethoxy-3,3,5,5-tetrachloro-8-oxabicyclo[4,3,0]-noan-2,4-dione (I), and methyl chloro-(2,5-dihydro-5-methoxy-2-furanylidene) acetate (II). The reactions of 2,5-dihydrofuran and 2,5-dimethoxy-tetrahydrofuran with dichloroketene were also-studied for comparison. Compound II was derived from the insertion of a molecule of dichloroketene into the C-O bond of DDF with subsequent dehydrochlorination. Compound I resulted from the cycloaddition of two molecules of dichloroketene to the C=C bond of DDF. A mechanism involving a 1,5-dipolar intermediate is proposed to account for this novel reaction. 相似文献
4.
We have developed an efficient method for the synthesis of 2,5-dihydrofuran and 2,5-dihydropyrrole skeletons from the simply modified Baylis-Hillman adducts via RCM reaction. 相似文献
5.
V. Z. Shirinyan M. M. Krayushkin L. I. Belen'kii L. G. Vorontsova Z.A. Starikova A. Yu. Martynkin V. L. Ivanov B. M. Uzhinov 《Chemistry of Heterocyclic Compounds》2001,37(1):77-84
There is proposed, and in the case of 2,5-dimethylthiophene carried out, a novel route to the synthesis of 3,4-dithienylfuran-2,5-dione type photochromes. This is done in two stages, the first being a Friedel-Crafts reaction of the starting thiophene with the dichloride of squaric acid and the second is a Baeyer-Villiger oxidation of the 3,4-bis(2,5-dimethyl-3-thienyl)cyclobutenedione to give the target 3,4-bis(2,5-dimethyl-3-thienyl)furan-2,5-dione. 相似文献
6.
Pyrolysis of N-(1,5-dimethyl-2-pyrryl)methyl benzamide (7) gaved a 1:1 ratio of 1-methyl-2,5-dimethylene-2,5-dihydropyrrole (4b) and 1,2-dimetbylpyrrole (10) as the primary pyrolysis products in 88% total yield. The reactive compound 4b was detected with low-temperature 1H NMR spectroscopy. Upon warming, 4b reacted rapidly with 10 to give one-on-one, two-on-one and three-on-one adducts, 11, 12 and 13 , respectively. 相似文献
7.
Shanmugam Thiyagarajan Linda Gootjes Willem Vogelzang Jing Wu Jacco van Haveren Daan S. van Es 《Tetrahedron》2011,67(2):383-389
An efficient route towards the synthesis of 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol 4 has been developed resulting in significant improvements in both isolated yields and purity when compared to literature procedures. As a consequence, resin-grade 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol 4 has become available for laboratory scale step-growth polymer synthesis. Additionally, an interesting renewable chiral 2-amino-2-deoxy-1,4-3,6-dianhydroiditol 10, has been isolated. 相似文献
8.
L. G. Shagun L. V. Klyba I. A. Dorofeev E. R. Zhanchipova I. A. Mikhailova M. G. Voronkov 《Chemistry of Heterocyclic Compounds》2007,43(2):166-168
2,5-Dimercapto-2,5-dimethyltetrahyrothiophene was synthesized by the reaction of 1-iodopropan-2-one with hydrogen sulfide
in an ether solution of hydrogen chloride at-70°C. Its structure was established by mass spectrometry, 1H and 13C NMR spectroscopy.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 216–219, February, 2007. 相似文献
9.
Takahito Itoh Toshio Nakamura Masataka Kubo 《Journal of polymer science. Part A, Polymer chemistry》1999,37(15):3027-3039
Novel 2,5-dimethylene-2,5-dihydrothieno[3,2-b]thiophene derivatives such as 2,5-bis[di(ethylthio)methylene]-2,5-dihydrothieno[3,2-b]thiophene ( 4b ) and 2,5-bis[cyano(ethylthio)methylene]-2,5-dihydrothieno[3,2-b]thiophene ( 4c ) were successfully synthesized as isolable crystals. Polymerization behavior of 2,5-bis(dicyanomethylene)-2,5-dihydrothieno[3,2-b]thiophene ( 4a ), 4b , and 4c was investigated. 4a , 4b , and 4c are not homopolymerizable with any initiators and also not copolymerizable with vinyl monomers such as styrene (St), methyl methacrylate, and acryronitrile except for an alternating copolymerization of 4a with St. 4a , 4b , and 4c did not copolymerize with 7,8-bis(butoxycarbonyl)-7,8-dicyanoquinodimethane (BCQ) as a highly conjugated comonomer and instead only homopolymer of BCQ was obtained, indicating that they are much less reactive than BCQ. To obtain the relative reactivity among 1c , 2c , and 4c , the rate of addition reaction of 2,2′-azobis(isobutyronitrile) (AIBN) with 4c was compared with those of AIBN with 7,8-bis(ethylthio)-7,8-dicyanoquinodimethane ( 1c ) and with 2,5-bis[cyano(ethylthio)methylene]-2,5-dihydrothiophene ( 2c ) by NMR spectroscopy and analyzed with the first-order kinetics. The relative reactivity among 1c , 2c , and 4c was found to be as follows: 1c > 4c > 2c . The relationship between structure and reactivity for the quinonoid compounds was discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3027–3039, 1999 相似文献
10.
Saravanan Gowrisankar 《Tetrahedron letters》2005,46(29):4859-4863
A facile synthetic method of 3,4-disubstituted 2,5-dihydrofurans and 2,5-dihydropyrroles starting from the Baylis-Hillman adducts was developed. The 2,5-dihydrofuran skeleton was constructed via the consecutive radical cyclization, hydrolysis, halolactonization, and spontaneous decarboxylation strategy starting from the modified Baylis-Hillman adducts. 相似文献
11.
Monika Kalinowska Liliana Mazur Agata Jabłońska-Trypuć Włodzimierz Lewandowski 《Journal of Saudi Chemical Society》2018,22(6):742-756
The structure and composition of the calcium 2,5-dihydroxybenzoate (calcium gentisate) were studied by single-crystal and powder X-ray diffraction. Single-crystal X-ray analysis revealed that the compound crystallizes in the orthorhombic space group Pbcn. The Ca(II) cation is coordinated in a monodentate fashion by two symmetry-related gentisate anions and five water molecules. The metal ion and one of the water molecules are located on a 2-fold rotation axis. The adjacent monomeric units are assembled into a 3-D supramolecular framework via O–H…O hydrogen bonds. Comparison of the experimental powder pattern with that simulated from single-crystal X-ray data confirmed the purity and homogeneity of the sample. The FT-IR, UV/VIS, 1H and 13C NMR spectra of the calcium 2,5-dihydroxybenzoic acid were registered and analysed. Moreover the effect of calcium complex and 2,5-dihydroxybenzoic acid on basic oxidative stress parameters, such as thiol group content and lipid peroxidation in the human breast cancer cells MCF-7 was studied. The antiradical and ferric reducing power of these compounds was measured by DPPH, CUPRAC and FRAP methods. The chemical reactivity parameters (e.g. HOMO and LUMO orbitals, ionization potential, electron affinity) for Ca 2,5-dHB and 2,5-dHB were calculated at B3LYP/6-311++G7 level of theory and discussed in relation to their antioxidant properties. 相似文献
12.
L. D. Patsenker I. G. Ermolenko O. N. Lyubenko I. A. Fedyunyaeva N. A. Popova O. S. Galkina A. V. Mazepa B. M. Krasovitskii 《Chemistry of Heterocyclic Compounds》2003,39(4):525-533
It has been shown that dimethylamino-substituted 2,5-diaryloxazoles and 2,5-diaryl-1,3,4-oxadiazoles undergo heterocyclization under Vilsmeier-Haack conditions with the participation of the dimethylamino group to form quinazolinium salts. The oxazole ring can also be formylated at the free 4 position. In alkaline medium the quinazolinium ring is readily hydrolyzed with desalkylation. 相似文献
13.
Valeria Di Bussolo Salvatore Princiotto Vittorio Bordoni Elisa Martinelli Lucilla Favero Stefano Crotti Gloria Uccello Barretta Federica Balzano Mauro Pineschi Paolo Crotti 《Tetrahedron》2019,75(33):4425-4443
Upon treatment with the metal enolates of methylene active compounds (dimethyl malonate and dibenzoylmethane) (C-nucleophiles) and benzyl carbamate (N-nucleophile), d-allal- and d-galactal-derived vinyl epoxides are stereoselectively transformed, in a single step, into diastereoisomeric, highly functionalized, enantiopure cis- and trans-2,5-disubstituted-2,5-dihydrofurans. 相似文献
14.
15.
A novel method for the synthesis of 2,5-disubstituted-1,3,4-thiadiazoles via direct ring closure of 1,6-disubstituted-2,5-dithioureas in dimethylformanide without using any ring-closing reagents has been accidentally discovered. Repeated and extended experiments confirmed that this is a very simple and efficient way to synthesize these kinds of fine chemicals. A series of novel 2,5-disubstituted-1,3,4-thiadiazoles have been synthesized via this method in good yields. 相似文献
16.
A. I. Kovalev K. Takeuchi M. Asai M. Ueda A. L. Rusanov 《Russian Chemical Bulletin》2004,53(8):1749-1754
Conditions were found for selective cross-coupling of 1-ethynyl-2,5-dihexyl-4-iodobenzene with arylethynyl-activated arylacetylenes. The reaction is not accompanied by homo-condensation of 1-ethynyl-2,5-dihexyl-4-iodobenzene.Published in Russian in Izvestiya Akademii Nauk.
Seriya Khimicheskaya, No. 8, pp. 1682–1687, August, 2004. 相似文献
17.
Bio-based poly(isosorbide 2,5-furandicarboxylate-co-ε-caprolactone) (PIFCL) copolyesters were synthesized from 2,5-furandicarboxylic acid, isosorbide and ε-caprolactone. The obtained copolyesters were characterized by 1H NMR, 13C NMR, intrinsic viscosity, GPC, DSC, TGA and tensile testing. The NMR characterization results confirmed the insertion of lactones units into poly(isosorbide 2,5-furandicarboxylate) (PIF) chains. All PIFCL copolyesters were amorphous with TD, 5% higher than 300 °C. The glass transition temperatures of PIFCLs with FDCA molar ratio from 74% to 45% were within the range of 132.1 °C and 72.4 °C. Tensile testing revealed that introduction of ε-caprolactone into PIF chain imparted PIFCL with excellent mechanical performance, typically, PIFCL polyseter with FDCA molar ratio of 45% had a Young's modulus 858 ± 92 MPa, a tensile strength 44 ± 4 MPa and an elongation at break 480 ± 45%. 相似文献
18.
19.
R. Garzelli 《Tetrahedron》2008,64(19):4183-4186
2,5-Dimethoxy-2,5-dihydrofuran is a synthetic equivalent of 2(5H)-furanone or 2-trimethylsilyloxyfuran, useful C4 synthons in the preparation of 5-substituted-2(5H)-furanone derivatives. The reaction conditions adopted allow to obtain different classes of complex and biologically interesting compounds, in only one step, with high yields. 相似文献
20.
Tiantian WangJia Liu Zhiliang LvHanyu Zhong Huan ChenChunjuan Niu Ke Li 《Tetrahedron》2011,67(19):3476-3482
An efficient and mild synthesis of highly substituted 2,5-dihydrofuran and furan derivatives from a variety of alkylidene malonates and 1,4-butyne-diol via one-pot reaction was applied. With various conditions of base amount, temperature and time applied to the reaction, the 2,5-dihydrofuran and the furan derivatives could be selectively obtained. Moreover, the formation of furan derivatives with 2,5-dihydrofuran derivatives as intermediates was also investigated. Some of these 2,5-dihydrofuran derivatives showed potent in vitro anti-tumor activities against HeLa cells. 相似文献