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1.
Reaction of a number of aryl styryl ketones with polyphosphoric acid has been investigated and, with the exception of 9-anthryl styryl ketone, each undergoes smooth cyclisation to give an isomeric 5-membered ring ketone. The polyphosphoric acid- and aluminium chloride-catalysed cyclisations of 1-naphthyl styryl ketone, which give 3-phenyl-2,3-dihydrobenz(e)inden-1-one and phenalen-1-one respectively, are discussed and a general interpretation of the cyclisation modes of 1-naphthyl substituted ketones and carboxylic acids in terms of the HSAB theory is offered. 相似文献
2.
An efficient and stereoselective total synthesis of C-nor D-homosteroid compounds is described, following a general pathway of the A→B→C→D type. The A-B ring system was provided by the Wieland-Miescher ketone
. the ring C was formed by intramolecular cyclisation of an appropiate γ-diketone such as
. Construction of the ring D was achieved by means of a Birch reductive alkylattion, followed by intramolecular cyclisation of the intermediate δ-diketone thus formed. C-nor D-homosteroids
and
having six asymmetric carbons as well as the required “natural”
configuration were thus obtained in eleven steps from the Wieland-Miescher ketone
. 相似文献
3.
Beln Altava M. Isabel Burguete Eduardo García-Verdugo Santiago V. Luis Juan F. Miravet María J. Vicent 《Tetrahedron: Asymmetry》2000,11(24):4885-4893
New C2 symmetric TADDOLs containing different groups at the 2-position of the dioxolane ring have been prepared. The Ti catalysts derived from these have been studied in the Diels–Alder reaction of cyclopentadiene and (E)-2-butenoyl-1,3-oxazolidin-2-one. Substituents at the C-2 position of the dioxolane ring can play an important role in determining the selectivity as well as the nature of the major isomer. This effect is more important for TADDOLs containing bulky aromatic groups such as 3,5-dimethylphenyl- or 1-naphthyl at the -positions. Experimental evidence supports the hypothesis that π–π interactions between aromatic groups at the C-2 and the ones at the -positions are critical in this respect. 相似文献
4.
The microwave spectra of chlorobenzene “(1)-35Cl”, all eight mono-[“(1)-37Cl”, “(1)-35Cl, (2)D”, “(1)-35Cl, (3)D”, “(1)-35Cl, (4)D”, “(1)-35Cl, (1)-13C”, “(1)-35Cl, (2)-13C”, “(1)-35Cl, (3)-13C”, “(1)-35Cl, (4)-13C”], one di[“(1)-35Cl, (2,6)D2,”] and one trisubstituted species [“(1)-37Cl, (2,6)D2”] have been investigated. From the moments of inertia of the vibrational ground state the rs structure was derived. The reliability of the two small a coordinates could be enhanced through use of the multiply substituted species. The errors of the moments of inertia were propagated to the structural parameters. It could be shown that the benzene ring is deformed. However the quantitative deformation could not be established due to the rather large errors of some structural parameters. 相似文献
5.
Interactions between ethylselenoglycollic, selenoglycollic and ethylene-bis- selenoglycollic acids and some “soft”, “borderline” and “hard” metallic ions have been studied. The interactions of [PdCl4]aq2− with the three ligands were verified conductometrically and spectrophotometrically. The stability constants β1 and β2 for the system [PdCl4]2-- ethylene-bis-selenoglycollic acid have been determined at 25°C at ionic strength 3.0 M (NaCl). The stoichiometric ionization constant of the mentioned acid was also studied. 相似文献
6.
《Tetrahedron letters》1987,28(40):4681-4684
7-hydroxy-TTNN, a possible metabolite of the aromatic retinoid: 6-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-2-naphthoic acid (TTNN) (2), was synthesized through a short route, the key step of which was a one pot oxidation/cyclisation/aromatisation of a 1,5 diol to afford the phenolic ring C (see scheme 1). 相似文献
7.
Larisa Golender Hanoch Senderowitz Benzion Fuchs 《Journal of Molecular Structure》1996,370(2-3):221-236
The energy differences between stereoisomers and the ring inversion potential surfaces of decalin (1) and various oxadecalins (2, 3), dioxadecalins (4–7), trioxadecalins (8, 9) and tetraoxadecalins (10, 11) were interrogated following the generally accepted scheme of a stepwise conformational six-ring inversion process and using molecular mechanics techniques (MM3 and MM3-GE, i.e. MM3 reparametrized for treatment of the “gauche effect”). The results were compared with some available experimental data and were also used to probe the validity of a recently elaborated protocol for ring-fragment analysis of oxygen-containing bicyclic systems in terms of their interannular fragment components: C---C---C---C, C---C---C---O, C---C---O---C, C---O---C---O---C and O---C---C---O, the latter two with their corresponding stereoelectronic effects, namely, the “anomeric effect” and the “gauche effect”, respectively. 相似文献
8.
Yves Leroux Driss El Manouni Brahim Ben Jaafar Ramon Burgada 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):205-208
Abstract - Addition of trivalent phosphorus compounds with α, β ethylenic ketones and esters leads to examples of prototropy or cyclisation or rearrangement with ring expansion from 5 to 7 atoms. When trivalent phosphorus compounds react with acetylenic ketones and esters, the 1, 3 dipolar species can be trapped with an electrophilic reagent (aldehydes or the original acetylenic compound) or a protic reagent (alcohol, acid, amide, phenol, etc…) Ylides, phosphoranes, spirophos-phoranes and phospholes can be obtained. 相似文献
9.
Dimethylacetylenedicarboxylate reacts with Fischer's base (1,3,3-trimethyl-2-methylene indoline) to give a zwitterionic intermediate which undergoes a Michael type addition in MeOH or cyclisation and ring opening in CHCl3 to yield isomeric dienamines. Methyl propiolate, in addition to both the products observed previously, gives the ω-methoxycarboxylated Fischer's base in CHCl3, whereas in CCl4 a chlorinated dienamine is obtained. The solvent effect has been rationalised. Some dienamines react with tosylated oximes yielding azatrienes. The structures of the reaction products have been assigned on the basis of spectral data. A large difference of NMR chemical shift for the methyl groups bonded to the indoline ring has been observed depending upon the E and Z structure of the substituted Fischer's base. 相似文献
10.
The complex Fe(η6-C5H5CMe3)2 crystallizes in the centrosymmetric triclinic space group P
(Ci1; No. 2) with unit cell dimensions of a 8.770(1) Å, b 8.878(1) Å, c 11.991(1) Å, 107.56(1)°, β 90.85(1)°, γ 90.13(1)°, V 890.0(2) Å3 and Z = 2. A full sphere of data was collected on a four-circle diffractometer. The structure was solved and refined to R 7.93% for all 3155 independent reflections and R 4.98% for those 2002 data with | F0 | > 6σ. | F0 |. The molecules lie on crystallographic inversion centers at 0, 0, 0 and 1/2, 0, 1/2; the crystallographic asymmetric unit therefore consists of two independent half molecules. The molecule centered at 0, 0, 0 (molecule “A”) is ordered and well-defined; that centered on 1/2, 0, 1/2 (molecule “B”)is probably disordered, as indicated by larger “thermal parameters” and a greater range of apparent interatomic distances. Discussion em phasizes the geometry of molecule A, which has precise Ci symmetry with Fe(1A)-B(1A) 2.297(4) Å and Fe(1A)-C(ring) distances ranging from 2.057(6) Å to 2.138(4) Å. 相似文献
11.
New tricyclic quinoxalinone skeletons with bridge-head nitrogen atoms and containing sulphur in a fully-reduced five-membered ring C were obtained. 3,3a-Dihydrothiazolo[3,4-α]quinoxalin-4-ones I-III were prepared by metal-acid reductive cyclisation of N-(nitrophenyl)- and N-(dinitrophenyl)thiazolidine-4-carboxylic acids IVa,b,c. Attempts to obtain the skeleton by selective hydrogen transfer reductive cyclisation of the corresponding esters Va,b,c were unsuccessful. 相似文献
12.
In order to explain the difficulty in hydrolysing the lactam linkage of 1-benzyl-2-oxo-5-ethyl-4-piperidineacetic acid (XIV) under acid conditions, several model compounds such as 1-benzyl-2-piperidone (X), 1-benzyl-5-ethyl-2-piperidone (XI), 1-benzyl-4-ethyl-2-piperidone (XII) and 1-benzyl-2-oxo-4-piperidineacetic add (XIII) were prepared and their hydrolysis in boiling 6N HCl was studied. For each of the lactams, the hydrolysis was found to proceed to an equilibrium as shown in Table 1. Substituents at the 4- and 5-positions of the piperidone ring seemed to favour the ring form in the equilibrium between piperidones (X-XIV) and ω-amino acid hydrochlorides (type XV). 相似文献
13.
H. Lucas J. E. M. Hasten Th. G. van Dinther D. G. Meuleman S. F. van Aelst C. A. A. van Boeckel 《Tetrahedron》1990,46(24):8207-8228
The syntheses of four analogues of pentasaccharide Ia, which corresponds to the minimal AT III binding region of heparin, are presented and the biological activities of these analogues will be discussed. Three of these analogues (i.e. compounds II, III and IV) contain an R-glyceric acid oxymethylene residue (i.e. B in fig.3) instead of -L-iduronic acid and in the other analogue (i.e. compound V) the β-D-glucuronic acid unit has been replaced by an s-glyceric acid oxymethylene residue (i.e. A in fig3). The R and S-glyceric acid oxymethylene residues represent an “opened” iduronic acid unit and an “opened” glucuronic acid unit, respectively, containing the essential carboxylate function in the appropriate configuration. The crucial step in the syntheses of these “opened” uronic acid pentamer analogues, was the preparation of the required glyceric acid oxymethylene residues 8a, 8b and 8c.
Analogues II and III, containing an “opened” iduronic acid moiety, display a significant AT III mediated Xa activity. Compound III contains two extra sulphate groups at unit 2. Removal of the contributing O-sulphate groups at position 3 and 6 of unit 6 of compound II (i.e. compound IV) results in a seven-fold drop in Xa activity. Replacement of the β-D-glucuronic acid unit by an S-glyceric acid oxymethylene residue (i.e. compound V) leads to almost a complete loss of Xa activity, notwithstanding the fact that all the essential and contributing charged groups are present in the molecule. 相似文献
14.
N. S. Koslov G. S. Shmanai L. F. Gladchenko 《Chemistry of Heterocyclic Compounds》1985,21(11):1268-1272
By condensation of 9-[N-(2-naphthyl)formimidoyl]anthracene with methyl ketones under conditions of acid catalysis, 1-R-3-(9-anthryl)benzo[f]quinolines have been obtained. The byproducts of the reaction have been identified: 1-R-3-(9-anthyl)-2-propen-1-ones and N-[1-(p-aminophenyl)-3-(9-anthryl)-2-propen-1-ylidene]-2-naphthylamines. The spectral and luminenscence properties of these compounds have been examined critically.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1536–1541, November, 1985. 相似文献
15.
The new term “Phanes” has been clearly defined and a nomenclature system tentatively developed. This system is comprehensible and of general application and at the same time relatively simple. The notations “nucleus”, “bridge”, “number of bridge members” and “number of ring members” are defined. In order to get a definite characterisation of the phanes which contain a carbocyclic nucleus, a carbocyclic and heterocyclic bridge the following terms: “carbophanes”, “carba-phanes” and “hetera-phanes” have been newly introduced. The prefix “hetera-” has been proposed as a general expression and as a representative term for the syllables “aza-”, “oxa-”, “thia-” and so on. The so called “a-nomenclature” is clearly called “hetera-nomenclature”. The new expressions “heteralogous” and “substitulogous” are explained. As the various examples will show, the “Phane-Nomenclature” can also be applied to the naming of complicated metallocenophanes. 相似文献
16.
An aromatic sesquiterpene, cuparene (IV), has been isolated from Chamaecyparis thyoides, Biota orientalis and Widdringtonia. Cuparene gives terephthalic acid on oxidation with dilute nitric acid and (+)-camphonanic acid (III) on prolonged treatment with ozone and is therefore 1-(4-methylphenyl)-1:2:2-trimethylcyclopentane. Oxidation of cuparene with chromium trioxide gives the corresponding substituted benzoic acid, cuparenic acid (V). This acid has been found to be identical with one of the sesquiterpene acids (“acid III”) previously isolated from Widdringtonia species and now also from Chamaecyparis thyoides. 相似文献
17.
The regio- and stereoselective addition of chlorosulfonyl isocyanate to (+)-3-carene 1 resulted in β-lactam 2, which was converted to N-Boc-β-amino acid 4, β-amino ester 7, and carboxamide derivatives 18 and 20 via N-Boc activation and mild ring opening. The corresponding β-amino ester 7 was transformed to 2-thioxopyrimidin-4-one 11 and 2,4-pyrimidinedione 13. LAH reduction of 5 and 7 resulted in amino alcohols 6 and 8. The reaction of 8 with phenyl isothiocyanate, followed by cyclisation, furnished 1,3-oxazine 15. 相似文献
18.
Mototeru Yamane Akihisa Abe Shinsuke Shimizu Masato Nakajima 《Journal of chromatography. A》1996,730(1-2):91-98
A homogenate of rat brain, rat liver or human colonic well differentiated adenocarcinoma was prepared in 250 mM sucrose isoosmolaric buffer (pH 7.6) and fractionated by differential centrifugation at 103, 104 and 105 g. Each precipitate or supernatant was incubated with NADPH and docosahexaenoic acid or arachidonic acid as a substrate for 30 min at 37°C under aerobic conditions. ω-Hydroxydocosahexaenoic acid or ω-hydroxyeicosatetraenoic acid from an incubation mixture was detected by reversed-phase high-performance liquid chromatography-thermospray mass spectrometry with selected-ion monitoring. ω-Hydroxy polyunsaturated fatty acids were characterized by high intensity of the molecular ion (MH+) although common hydroxy polyunsaturated fatty acids were characterized by high intensity of the MH+ - H2O ion. For the rat brain, ω-hydroxylation activity (the amount of ω-hydroxy product produced in 30 min) was concentrated to a 103 g precipitate although the specific activity (the activity per 1 mg of protein) in the 103 g precipitate did not indicate superiority over other fractions. However, the specific activity of the rat brain increased on addition of a 104 or 105 g precipitate. For the rat liver, although ω-hydroxylation activity was concentrated to a 103 g precipitate, the specific activity was concentrated to a 105 g precipitate and the Subcellular localization differed from that of rat brain. In the human colonic well differentiated adenocarcinoma, although ω-hydroxylation activity was relatively high in the 103 g supernatant, the specific activity was relatively high in the 103 and 105 g precipitates. These results suggest that there is a difference regarding subcellular localization of the ω-hydroxylation activity depending on the species of the organs. 相似文献
19.
By reinvestigation of “isomiropinic” and “miropinic” acids from the bled resin of Podocarpus ferrugineus, the compounds have been identified as sugiol and isopimaric acid respectively. The identity of the resin acid from Dacrydium biforme has been confirmed as isopimaric acid. 相似文献
20.
Gerhard Erker Michael AulbachCarl Krüger Stefan Werner 《Journal of organometallic chemistry》1993,450(1-2):1-7
Isopinocamphyl-tosylate (2) was treated with indenyllithium to yield 3-(neoisopinocamphyl)-indene (3). Treatment of 3 with methyllithium gave 1-(neoisopinocamphyl)indenyllithium (4) which was then treated with 0.5 molar equivalents of ZrCl4(thf)2 to give a 52:48 mixture of one of the “racemic-like” isomers of bis[1-(neoisopinocamphyl)indenyl]ZrCl2 (5A) and its “meso-like” diastereomer 5C. Hydrogenation of the 5A/5C mixture (50 bar H2, Pt) furnished a mixture of the corresponding tetrahydroindenylzirconium complexes 6A and 6C, from which the “meso-like” bis[1-(neoisopinocamphyl)-4,5,6,7-tetrahydroindenyl]zirconium dichloride diastereoisomer (6C) was isolated. Treatment of 6C with an excess of methylalumoxane in toluene/propene generated an active -olefin polymerization catalyst. At −30°C partly isotactic polypropylene (
η = 39000) was obtained. The catalyst derived from the chirally-substituted “meso-like” metallocene complex 6C produced polypropylene predominantly under enantiomorphic site control. 相似文献