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1.
The ‘Push-Poll’ Effect of ‘Push-Pull’ Oligoacetylenes. A 13C-NMR Investigation According to 13C-chemicaI shifts of ‘push-pull’ oligoacetylenes 1 – 4 , the ‘push-pull’ effect (i.e. π delocalization induced by ‘push-pull’ substituents) rapidly decays in this series. To correct for other than π -charge-density effects, Δδ values of symmetrically placed C-atoms of the oligoacetylene chain are discussed. Stereoelectronic resteffects (SER) of the substituents on terminal C-atoms of PP-ketones 1a – 3a and PP -esters 1b – 4b are estimated from the residual Δδ of the asymptotes of Fig. 3. Fig. 4 convincingly shows that Δδ values are dramatically decreasing with increasing number n of acetylene units between the push and pull substituents. Assignment problems of ‘push-pull’ triacetylenes 3 have been solved by 13C labelling of the CO group of 3a .  相似文献   

2.
Solid-State Polymerisation of a ‘Push-Pull’-Diacetylene Solid-state polymerisation of ‘push-pull’-diacetylene 5-(diphenylamino)-1-phenylpenta-2,4-diyn-1-one ( 1d ), initiated by heating of crystals of 1d at 90°, gives ‘push-pull’ poly-diacetylene 2d . X-Ray results and spectroscopic data of monomer 1d as well as of polymer 2d are discussed.  相似文献   

3.
Synthesis of ‘Push-Pull’-OligoAcetylenes ‘Push-pull’ triacetylenes 11a , b , c , as well as ‘push-pull’ tetraacetylene 13b have been prepared by reaction of the corresponding trichloroene(oligoinyl)amines 9 and 10 with 2 mol-equiv. of BuLi followed by acylation. The sequences (Schemes 3 and 4) are very simple and straightforward, they could in principle be applied to the synthesis of ‘push-pull’ pentaAcetylenes 15 and hexaacetylenes 17 (Scheme 5). Main limitations are the moderate yields as well as the low thermal stability of push-pull oligoacetylenes.  相似文献   

4.
Synthesis of ‘Push-Pull’ Diacetylenes The first synthesis of push-pull diacetylenes of type 1 is described. Reaction of perchlorobutenyne ( 8 ) with two equivalents of dialkylamine, followed by dechlorination using two equivalents of butyllithium gives lithio-dialkylamino-diynes 7 . Final acylation of these intermediates leads to push-pull diacetylenes 1b–1e in good yields. The method allows the introduction of both push and pull substituents in a simple one-pot-procedure. In addition, 1a is prepared by hydroxymethylation of lithio-morpholino-diyne 7c , followed by oxidation with manganese dioxide in acetone.  相似文献   

5.
Photoinduced Cycloadditions of 2,2-Dimethyl-3-phenyl-2H-azirine with Nitriles and ‘push-pull’ Olefines. Electron deficient nitriles of the type 5a–e in contrast to nonactivated nitriles undergo regiospecific [2+3]cycloadditions to benzonitrile isopropylide ( 2b ), which was generated in situ by irradiation of 2,2-dimethyl-3-phenyl-2H-azirine ( 1b ), to yield the 2H-imidazole derivatives 6a – e (Scheme 2). The structure of the photoproducts was mainly deduced from 13C-NMR. and mass spectrometry. Whereas normal olefins or enolethers do not react with 2b , push-pull olefins of the type 10a – d readily undergo the cycloaddition to give the 3-alkoxy-5,5-dimethyl-2-phenyl-1-pyrrolines 11a – d (Scheme 3 and 4). The structure of the photoproducts 11a – d indicates that the regiospecificity of the cycloaddition corresponds to that of acrylonitriles and acrylesters with 2b .  相似文献   

6.
Isolation and identification of evernine in ‘Oakmosse’ (Evernia prunastri (L. ) Ach.). A new depside, evernin ( 1 ), has been found in the lichen Evernia Prunastri (L. ) Ach. The determination of the structure and the spectral parameters of 1 , especially the 13C-NMR. spectrum, are described.  相似文献   

7.
The preparation of several kinds of derivatives of 1-substituted D -arabinc-hex-1-ene-3,4,5,6-tetrols is described. Some of these compounds, having a ‘pseudo-formyl’ group (? CH?CHCN, ? CH?CHSO2CH3) are ‘pseudo-aldehydo-sugars’. Their ability to react as aldehydo-sugars was examined in light of their 13C-NMR. spectra which provide information on their electron density at C(1) and C(2).  相似文献   

8.
Structure Determination of N6-, 9-and 7-Acyladenines by 1H- and 13C-NMR Spectroscopy of Solids and in Solution . Adenine (1) reacts with carboxylic acid anhydrides or chlorides 2 to yield the acyladenine isomers 3–5 . The isomeric structures were determined by 33C- and 1H-NMR spectroscopy in solution and by solid-state 13C-NMR spectroscopy.  相似文献   

9.
New Heteroarenes: Synthesis and Spectroscopic Properties of Indolizino[6,5,4,3-aij]quinoline (‘Ullazine’) and of some Derivatives The synthesis, 1H-NMR, 13C-NMR and electronic absorption spectra of indolizino[6,5,4,3-aij]quinoline (6a) , a new π-excess heteroarene, and of three 3,9-disubstituted derivatives are described.  相似文献   

10.
The Structure of the Alkaloid Juliprosopine from Prosopis juliflora A. Dc. A new alkaloid, juliprosopine, has been isolated from Prosopis juliflora A. Dc. (Leguminosae), for which structure 1 is proposed. The piperidine moiety could be elucidated on the basis of spectroscopic data (MS., 1H-NMR., 13C-NMR.) of juliprosopine and the derivatives 2–4 . The central hexahydroindolizine part and its substitution pattern has been determined mainly on the bases of the Hofmann-degradation product 11 , which yielded the hydrogenation products 13 and 14 . By ozonolysis 11 was converted to 16 and 18 . It is proposed that juliprosopine was built up in nature by two ‘monomeric’ Prosopis alkaloids and one dihydropyrrol unit.  相似文献   

11.
A 2D and variable-temperature 13C-NMR study indicates that a CO-site exchange occurs in the title complex via several consecutive processes, the first being a ‘merry-go-round’ of the basal CO's, the second a switch of basal face not involving unbridged intermediates.  相似文献   

12.
The title complex crystallises in two C3v, isomeric forms differing in carbonyl-ligand arrangement. In solution, the isomer 1b with three edge-bridging carbonyls on a common face of the metal tetrahedron converts via an endothermic equilibrium into the isomer 1u with no bridging carbonyls. The latter was shown by 13C-NMR to be the intermediate of the ‘merry-go-round’ process which exchanges the sites of the basal CO's.  相似文献   

13.
Monomers with leucine–tyrosine linkages were synthesized using diphenyl phosphoryl azide as a coupling reagent. Leucyltyrosylpoly(propylene glycol) bis(2-aminopropyl ether) tyrosylleucine (monomer 1 ) has a longer spacer: poly(propylene glycol) bis(2-aminopropyl ether) (Jeffamine® D-400), and leucyltyrosyliminohexamethyleneiminotyrosylleucine (monomer 2 ) has a shorter spacer: hexamethylenediamine. Polyureas from monomers 1 and 2 with hexamethylene diisocyanate and methylenedi-p-phenyl diisocyanate were synthesized. Polyamide, polyesteramide from monomer 2 were synthesized. The characterization of these polymers using 1H-NMR, 13C-NMR, solid-state 13C-NMR, IR, GPC, and also thermal analysis are presented. © 1997 John Wiley & Sons, Inc.  相似文献   

14.
8α,9α-Epoxy-7-oxoroleyanone, a Diterpenoid Epoxyquinone from an Abyssinian Plectranthus Species (Labiatae) Reexamination of the title plant, in additon to the previously identified abietanoid hydroxy-1,4-benzoquinones 1a, 1b, 1c, 1e, 1f, 1g , and 1h , yielded the known 7α-acetoxyroleanone ( = 7-O-acetylhorminone; 1d ) and the novel 8α, 9α-epoxy-7-oxoroyleanone ( 2a ). Spectroscopic methods, partial synthesis by epoxidation of 7-oxoroyleanone ( 1h ), and chiroptical correlation establish the structure 2a . Royleanone 2a is the first diterpenoid epoxyquinone isolated so far. Moreover, a detailed 13C-NMR analysis of the royleanones 1b, 1c, 1e, 1g , and 1h lead to the complete assignment of their spectra.  相似文献   

15.
The natural abundance 13C n.m.r. spectra of a series of para-substituted ethylbenzenes, 4-substituted-1-ethylnaphthalenes and a limited series of 6-substituted-2-ethylnaphthalenes have been examined at low dilution in deuterochloroform solvent. The ethyl carbons and Cipso in the phenyl series (i.e. have been assigned, and substituent chemical shifts for these carbons calculated and analysed by the Dual Substituent Parameter treatment. (Chemical shifts of all ring carbons have been obtained, but not assigned). Generally speaking, electron-withdrawing substituents lead to positive (i.e. downfield) substituent chemical shifts for CH 2 and negative substituent chemical shifts for C H3, i.e. ‘normal’ and ‘inverse’ behaviour respectively. Cipso in the phenyl series exhibits a ‘normal’ dependence. The dependences of the various substituent chemical shifts on inductive and resonance parameters are discussed, and compared with the behaviour of side chain carbons in other substituted benzene systems.  相似文献   

16.
Attempted Synthesis of Push-Pull Diacetylenes Two alternative synthesis of push-pull diacetylenes of type 1 (5-amino-2,4-alkadiynals) are investigated. A bromination-dehydrobromination sequence starting with 5-dimethylamino-2,4-pentadienal ( 2 ) as well as the application of the well-known Cadiot-Chodkiewicz coupling reaction give new intermediates 3–5 , and 7 and 8 , respectively, but fail to give the target molecules 1 .  相似文献   

17.
The title compounds, 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been synthesized by reacting various 4‐hydroxy coumarins 1a , 1b , 1c with 2‐arylidene‐1‐tetralones 2a , 2b , 2c , 2d in the presence of ammonium acetate and acetic acid under Krohnke's reaction condition. The structures of all the synthesized compounds were supported by analytical, IR, 1H‐NMR, and 13C‐NMR data. All the synthesized compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been screened for their antibacterial activities against Escherichia coli (Gram ?ve bacteria), Bacillus subtilis (Gram +ve bacteria), and antifungal activity against Candida albicans (Fungi). J. Heterocyclic Chem., (2011).  相似文献   

18.
The cyclopentenecarbaldehyde 1a , acetals 2a , 2b and the cyclopentenone 2c have been transformed through regio and stereocontrolled reactions into a variety of enantiomerically pure substituted cyclopentanes. Using appropriately selected Wittig reagents, aldehyde 1a furnished the condensation products 3 , 4 , 5 . Michael addition of diethyl malonate on the α,β-unsaturated aldehyde 1a under phasetransfer conditions led efficiently to 7 . Reduction of the cyclopentenone 2c gave 21 in high yield. The cyclopentenes 2a , 2b and 23 , submitted to hydroboration-oxidation furnished the cyclopentanols 10 , 13 and 24 , respectively, in 30, 70 and 50% yields, reflecting the substitution pattern of the starting alkenes. The salient feature of these reactions is the stereospecificity due to the chiral centre of the molecules 1a , 2a , 2b and 2c , leading to compounds with two, three and four asymmetric centres. The straightforward synthesis of 11α-hydroxy-13-oxaprostanoic acid 20 is described and an approach towards the preparation of 9α, 11α-dihydroxy-13-oxaprostanoic acid 34 is also presented. The structure of these products has been determined by 1H- and 13C-NMR spectroscopy.  相似文献   

19.
Some new (S)‐1‐aryl‐N‐(1‐hydroxy‐3‐phenylpropan‐2‐yl)‐5‐methyl‐1 H‐1,2,3‐triazole‐4‐carboxamides 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j have been synthesized and established by 1H and 13C NMR, IR, MS spectra, CHN analyses, and x‐ray diffraction crystallography. The molecular conformation and packing is stabilized by interactions of intermolecular H‐bond O2’‐H2'···O1, O2‐H2···O1’ and intramolecular H‐bond N4’‐H4'N···N3’, N4’‐H4'N···O2’, N4‐H4N···N3, N4‐H4N···O2. The two rings of five numbers were formed by H‐bond in a molecular.  相似文献   

20.
The configuration and favoured conformations of 1,2-dialkyl-(or alkyl-phenyl)-7-azabicyclo[4.1.0]heptane diastereoisomers have been determined by means of 13C NMR. The substituent in position-2 is ‘pseudo-axial’ in cis isomers and ‘pseudo-equatorial’ in trans isomers.  相似文献   

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