共查询到20条相似文献,搜索用时 31 毫秒
1.
To study flavin-flavin interactions [3.3](3,10)isoalloxazinophane was synthesized and its structure determined as . Electron spectra including charge-transfer absorptions of semi-reduced states are reported for in comparison with the mono-bridged bis-flavin analogue . 相似文献
2.
J. Nishimura M. Furukawa S. Yamashita T. Inazu T. Yoshino 《Journal of polymer science. Part A, Polymer chemistry》1981,19(12):3257-3268
The compound 1,3-bis(4-vinylnaphthyl)propane was prepared by a convenient dehydration of 1,3-bis[4-(1-hydroxyethyl)naphthyl]propane. The structure was confirmed by nuclear magnetic resonance (NMR) spectroscopy. The monomer was polymerized by antimony pentachloride, tin tetrachloride, titanium tetrachloride, or boron trifluoride etherate at 0°C in toluene, 1,2-dichloroethane, or a mixed solvent of 1,2-dichloroethane and nitromethane. Most of runs except for antimony pentachloride–catalyzed ones gave mainly benzene-soluble polymers. The structures of the polymers were studied by several spectroscopic methods. Comparison of NMR and fluorescence spectroscopic data of the polymers with those of syn-and anti-[3.3](1,4)napthalenophane was especially valuable in leading to the conclusion that they were cyclopolymers containing predominantly syn-[3.3]-(1,4)naphthalenophane units in the main chain. 相似文献
3.
《Tetrahedron letters》1986,27(17):1929-1932
Preferred conformation of the dithia[3.3]azulenofurano- ( and ) and thiophenophanes ( and ) were examined by PMR and X-ray crystallographic analysis. While the furanophanes prefer syn conformation, the thiophenophanes exist mainly in anti form. Free energy of activation for flipping of azulene and thiophene was evaluated separately for the latters. 相似文献
4.
Piotr Kus 《Journal of mass spectrometry : JMS》1991,26(7):653-654
The mass spectral fragmentation of 23 dithia [3.3]naphthalenophanes is discussed. The most characteristic species for these compounds are the M+ ion and ions at m/z 115, 135 (or 136), 141, 155 (or 154) and 185. 相似文献
5.
The crystal and molecular structure of [2.2](2,5)furano(1,4)naphthalenophane (1) was determined by X-ray crystallography. The molecule exists in the anti-conformation and the study represents the first instance in which the structural features of a naphthalenoid ring within a cyclophane were determined. Crystals of cyclophane 1 are orthorhombic, space group Pbca, with a = 7.859(2). b = 11.482(3) and c = 28.818(8) Å. While the nonbridged portion of the naphthalenoid ring is planar, the portion which is bridged to the furanoid ring through its 1 and 4 C atoms is puckered and boat-shaped. These C atoms are positioned 14° out of the plane of the other four C atoms of this ring. The furanoid ring is essentially planar but is not parallel to the naphthalenoid ring. It is inclined 22° to the least squares plane of the bridged portion of the naphthalenoid ring. This angle of inclination staggers the atoms of the furanoid and bridged naphthalenoid ring and positions the 3 and 4 C atoms, the 2 and 5 C atoms and the 0 atom of the furanoid ring 3.4. 2.9 and 2.6 Å. respectively, from the least squares plane of the bridged portion of the naphthalenoid ring. While the internal angles around the bridging C atoms α- to the naphthalenoid ring are 109°, those α- to the furanoid ring are 113°. In addition unusually large bond angles (137°) at the 2 and 5 C atoms of the furanoid ring, external to the ring, are also observed. The distortions are considered with respect to the strain within the cyclophane macrocycle and are compared with other similar systems. 相似文献
6.
The synthesis of -[3.3]metacyclophane quinhydrones and their thermal rearrangement to -stereoisomers are described. Charge-transfer absorptions are discussed under the aspect of different donor-acceptor orientations. 相似文献
7.
Dihydropyrrolo[3,2-b]pyrrole was synthesized starting from 1,4-bis(trimethylsilyl)benzene. 相似文献
8.
A sequence of formylation followed by a carbene insertion reaction has led to the stepwise introduction of additional ethano bridges into 4,5,7,8- tetramethyl [22](1,4)cyclophane (), providing syntheses of 5,7,8-trimethyl- [23](l,2,4)cyclophane (), a mixture of 5,8-dimethyl[24(1,2,4,5)cyclophane () and 5,7-dimethyl[24(1,2,3,5)cyclophane (, and-4-methyl[25](1,2,3,4,5)-cyclophane (). This route to completes a formal eight-step synthesis of [26](1,2,3,4,5,6)cyclophane (, superphane) with an overall yield of 17%. A Birch reduction of readily gave 12,15-dihydro-5,7,8-trimethyl[23](1,2,4)-cyclophane () in 85% yield. 相似文献
9.
Thermal nitrogen extrusion of 2-methylene-6,7-diazabicyclo[3.2.2]non-6-enes and 6,7- diazabicyclo[3.2.2]nona-2,6-diene,6 proceeded easily to give closure and cleavage products the corresponding 5-methylene-1,4-cycloheptylenes and 4-cyclohepten-1,3-ylenes, respectively. 相似文献
10.
Dichlorocyclopropanation as well as epoxidation of the 1,4-diarylbutadienes - to give the mono- and/or bisadducts according to several hindrance of large substituents as 2,6-dichlorophenyl. The bisadducts are formed preferably as - (or -) isomers. 相似文献
11.
The conformation of several -2,3-diaryloxy-1,4-dioxanes has been studied using 1H NMR techniques. -2,3-bis(4-nitrophenoxy)-1,4-dioxane and -2,3-bis(4-methoxyphenoxy)-1,4-dioxane have been found to be predominantly ( ≈98%) in diaxial conformation in CDCl3). On the other hand, -2,3-bis(2,6-dimethylphenoxy)-1,4-dioxane exists in the same conditions as a 66:33 mixture of diaxial and diequatorial conformers. An explanation based on the fulfilment of the exo-anomeric effect is provided. 相似文献
12.
Linda A. Motyka 《Tetrahedron letters》1985,26(24):2827-2830
Direct photolysis of 5-chloro-1,4-dihydro-9-methyl-naphthalen-1,4-imine in cyclohexane gave a mixture of 1-chloronaphthalene and isomeric dihydrocyclobut[b]indoles and . Dihydrocyclobut[b]indoles and thermally rearranged to give 1-benzazepines and , respectively. 相似文献
13.
In the paper a highly stereoselestive route to -1,4-di-tert-butylbutatriene --BuCu induced 1,3-substitution in ()--BuCHC(Br)CCH is described. 相似文献
14.
Uwe Keppeler Otto Schneider Werner Stöffler Michael Hanack 《Tetrahedron letters》1984,25(34):3679-3682
Conductivity of doped (μ-1,4-diisocyanobenzene)phthalocyaninatoiron(II)-compounds. - The (μ-1,4-diisocyanobenzene)phthalocyaninatoiron(II)-compounds , , and are doped with iodine leading to air stable powders which are stable up to 100°C. They were characterized by elemental analyses, TGA/DTA, IR-, resonance Raman- and 57Fe-Mössbauer spectroscopy. Increasing dopant levels result in higher electronic conductivities up to 10?2 S/cm and in decreasing activation energies. 相似文献
15.
M.C. Grossel A.K. Cheetham D.A.O. Hope K.P. Lam M.J. Perkins 《Tetrahedron letters》1979,20(15):1351-1354
X-ray crystallographic and solution 1H n.m.r. studies of -1,4-dihydro-4-tritylbiphenyl (2) both suggest the presence of an almost planar cyclohexa-1,4-diene ring (αmean = 1975°).4 相似文献
16.
Enantiospecific total synthesis of (-)-megaphone (1) is reported. The key synthetic tactic is the use of (4)-2-ethylidene-4-trityloxymethyl-butan-4-olide (6) to both establish the relative and absolute stereochemistry of the contiguous tertiary and quaternary carbon centers by a highly controlled 1,4- and 1,3-asymmetric induction and construct the 4-methoxy-6,6-dialkyl-cyclohexenone portion of 1. 相似文献
17.
G.W.J. Fleet S.J. Nicholas P.W. Smith S.V. Evans L.E. Fellows R.J. Nash 《Tetrahedron letters》1985,26(26):3127-3130
The syntheses of 1,4-dideoxy-1,4-imino-D-lyxitol (3), 1,4-dideoxy-1,4-imino-d-arabinitol (4) and 1,4-dideoxy-1,4-imino-l-arabinitol (5) are reported; (3) is a potent competitive inhibitor of α-galactosidase (green coffee beans) and (4) a competitive inhibitor of α-glucosidase (Brewer's yeast) suggesting that iminopentitols have considerable potential as glycosidase inhibitors. (4) was found to be identical to an alkaloid recently isolated from . 相似文献
18.
19.
The complexes trans-[PdCl{(ME)=NR'} (PPh3)2] (R=C6H11,p-C6H4OMe; R=p-C6H4OMe, Me) containing a σ-bonded 1,4-diaza-3-menthyl-butadiene-2-yl group with different substituents on the nitrogen atoms have been prepared by two routes. The first involves initial methylation of the mixed isonitrile complex [PdCl2(CNR)(CNR')]by HgMe2, followed by reaction with PPh3 (molar ratio ). The second method involves condensation of primary aliphatic amines with the carbonyl group of the 1-azabut-1-en-3-one-2-yl moiety of the complex trans-[PdCl{(Me) = 0} (PPh3)2]. The 1,4-diaza-3-methylbutadiene-2-yl derivatives act through their imino nitrogen atoms as chelating ligands towards anhydrous metal chlorides MCl2 (M = Co, Ni, Cu, Zn). Magnetic moment measurements and the far-infrared and electronic spectra of these adducts indicate an essentially pseudo-tetrahedral configuration at M in the solid and in solution. With the ZnCl2 adducts, the 1H NMR pattern for the phenyl protons of the p-methoxyphenyl N-substituents dependss upon the position of the substituent i the 1,4-diazabutadiene chain. 相似文献
20.
The hazard and inconvenience of storing and handling concentrated hydrogen peroxide can be avoided by using instead the solid complex which 1,4-diazabicyclo[2.2.2] octane forms with hydrogen peroxide, it reacts with trialkylchlorosilanes to give bis(trialkylsilyl) peroxides in good yield. 相似文献