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1.
Structure of deacetylazadirachtinol application of 2D1H-1H and 1H-13C shift correlation spectroscopy
Isao Kubo Takeshi Matsumoto Akiko Matsumoto James N. Shoolery 《Tetrahedron letters》1984,25(42):4729-4732
A new insect antifeedant, and ecdysis inhibitor deacetylazadirachtinol, was isolated from (Meliaceae) collected in Haiti and its structure (1) was elucidated by the spectral comparison with azadirachtin using two-dimensional 1H-1H and 1H-13C shift correlation spectroscopies. 相似文献
2.
The stereospecific synthesis of trans-decaline 2 is described. This compound is an important intermediate in the total synthesis of Clerodane insect antifeedants, as exemplified by ajugarin-I. 相似文献
3.
Mitsutoshi Yanagiya Fuyuhiko Matsuda Kazuo Hasegawa Takeshi Matsumoto 《Tetrahedron letters》1982,23(39):4039-4042
Total synthesis of optically active pedamide , one of the tetrahydropyran moieties of the potent insect poison pederine , was achieved by employing a new, remote controlled asymmetric reduction of a ketone as key step. 相似文献
4.
J.L. Breton F. Camps J. Coll L. Eguren J.A. Gavin A.G. Gonzalez X. Martorell C. Miravitlles E. Molins J. Torramilans 《Tetrahedron》1985,41(15):3141-3146
A new heliangolide has been isolated from aerial parts of , and identified as (6,10)(3,3a,4,lla)-3a,5,8,11a--tetrahydro-4-acetoxy-3,6, 1O-trimethyl-2,9 (3, 4) -cyclodeca[b] furandione. The structural elucidation of the new compound, named heliangolidin, was carried out by spectral means (MS, IR, 1H and 13C NMR, and two dimensional 1H-13C chemical shift correlations) and X-ray diffraction analysis. 相似文献
5.
W.David Ollis Julia Stephanidou Stephanatou J.Fraser Stoddart Gulten G. Unal David J. Williams 《Tetrahedron letters》1981,22(23):2225-2228
An X-ray structure analysis shows that the 5, 18-dimethyl derivative () of the title compound () crystallises from xylene as a 1:1 inclusion compound in which the host molecules adopt propeller-like conformations ( and *) with almost perfect 2 symmetry. Dynamic 1H n.m.r. spectroscopy shows that the 5, 18-dibenzyl derivative () of () forms a 1:1 inclusion compound with ethanol in the solid state and undergoes ring inversion ( ? *) between enantiomeric propeller-like conformations in solution against a barrier of 21.1 kcal mol?1 相似文献
6.
Shoji Ando Haruhiko Aoyagi Michinori Waki Tetsuo Kato Nobuo Izumiya Kouji Okamoto Michio Kondo 《Tetrahedron letters》1982,23(21):2195-2198
Gramicidin S (GS) analogs, (D-Ser(Bzl)4,4′]-GS (), [D-Ser4,4′]-GS (), and [L-Orn(Boc)2,2′,D-Ser4,4′]-GS () were synthesized and showed high antibacterial activity. One residue of D-Ser in was converted asymmetrically to D-Ala via α,β-dehydroalanine. 相似文献
7.
The synthesis of [O9,24] [2.1.2.1]metacyclophane-9-ene and of its dehydrogenation products^the new pyrenocyclophanes , , , and , is described; their structures are discussed in connection with their 1H-NMR-spectra. 相似文献
8.
Donald J. Burton 《Journal of fluorine chemistry》1982,21(1):47
The synthesis and mechanism of formation of phosphonium salts of the type [R3CFXY]Z? (where X = F, Cl, Br; Y = Br, Cl; Z = Br, Cl), -phosphonium salts of the type [R3CF2R3]2Br?, and phosphoranium salts of the type [R3FR3]X? (X = Br, Cl) will be presented. The applicability of these substrates in the generation of useful nucleophilic or electrophilic synthetic intermediates will be discussed. 相似文献
9.
The acid catalysed reaction of 4-oxa-homoadamantan-5-one () with benzene yielded a mixture of 4a-phenyladamantan-2-one (), the equatorial isomer' () and 2-phenyl-2,4-o- benzenoadamantane () A plausible reaction pathway for the occurrence of . is put forward. The structure of , was deduced from spectroscopic data and reaction of the proposed intermediate 2,4a-diphenyladamantan-2-ol () with acid. 2,4-o-Ben-zenoadamantane () is prepared likewise. 相似文献
10.
The optically active α-pyridyl-substituted diazocines and have been synthesized. They exhibit high rotation values and high optical stabilities. The helices and unexpectedly are highly Cu(I) selective chiral ligands. The CD spectra are strongly cation dependent. Cyclic voltammetry reveals strong differences between and its methyl-substituted analogue as to their Cu+ complexes. 相似文献
11.
Such an asymmetric [2,3]-Wittig variant that is both highly enantio- and erythro-selective is described within the context of the chiral synthesis of the insect pheromones, (3, 4)-4-methyl-3-heptanol and ()-4-methyl-3-heptanone. 相似文献
12.
The details and principles of an apparatus built for measurements of fluorescence quantum yields and cascade-free lifetimes of open-shell cations are reported. These rely on the detection of coincidences between energy selected photoelectrons and undispersed photons. The results of such measurements for CO+2, COS+, CS+2 and N2O+ in selected vibrational levels of their excited states are presented. Non-unity fluorescence quantum yields are found for some vibronic levels of CO+2(), COS+ (), N2OP+() and a non-exponential decay is observed for CS+2(). The data yield the following values for the radiative lifetimes: CO+2() 124 ± 6 ns, CO+2() 140 ± 7 ns, COS+() 550 ± 50 ns and N2O+() 240 ± 12 ns. 相似文献
13.
Kingiside aglucon () undergoes stereoselective addition of CH3OH to its C(3,4) enol ether double bond to give a C(1,3,9) diastereomer of xylomollin (), a secoiridoid aglucon that has insect antifeedant properties. 相似文献
14.
Preparation of potential insect antijuvenile hormone agents 2,2-dimethyl-7-(2,2,2-trifluoroethoxy)-2H-chromene (), 6-methoxy-2,2-dimethyl-7-(2,2,2-trifluoroethoxy)-2-chromene () and 7-methoxy-2,2-dimethyl-6--(2,2,2-trifluoroethoxy)-2-chromene () and the corresponding 3,4-epoxides and is reported. 相似文献
15.
David J. Herbert John R. Scheffer Anthony S. Secco James Trotter 《Tetrahedron letters》1981,22(31):2941-2944
Attempted intramolecular pinacolization of cage diketone unexpectedly gave ketol instead. Compound was shown to possess the rare tetracyclo[4.2.1.1.2,503,7]decane ring system by means of an X-ray crystal structure of hydroxy-mesylate derived from by sodium borohydride reduction followed by mesylation. A possible mechanism for the transformation of into is presented, and certain noteworthy features of the crystal structure of are discussed. The base-catalysed fragmentation of to give enone is also described. 相似文献
16.
Electron-deficient aromatics, such as 2,5-bis(trifluoromethylmercapto)thiophene () or (trifluoromethylmercapto)benzene (), react with F3CSCl in the presence of F3CSO3 as a catalyst to give mainly 3-chloro-2,5-bis(trifluoromethylmercapto)thiophen () and 1-chloro-4- or 2-(trifluoromethylmercapto)benzene (, respectively. This reaction competes with the one expected to result in 2,3,5-tris(trifluoromethylmercapto)thiophene () and 1,4- and 1,2-bis(trifluoromethylmercapto)benzene (,), respectively. Further reactions of deactivated aromatics with Cl3-nFnCSCl show that the chlorine substitution is in general catalysed by strong acids. Reaction mechanisms are proposed for both Substitutions. The Cl3-nFnCS group in aromatics exerts a -M-effect in the case of an attack of a positive ion, e.g. H⊕, the well-known +M-effect in the case of reactions with positively polarized molecules, e.g. CF3Sβ+Clβ-. 相似文献
17.
Fe2P4O12 has been prepared and identified as an isotype of the other MII2P4O12 tetrametaphosphates (MII = Ni, Mg, Cu, Co, Mn, Cd). Its monoclinic unit cell: contains 4 formula units. The space group is . For tetrametaphosphates with MII = Ni, Mg, Cu, Co, and Mn we found a new denser phase induced at 80 kbar and 1000°C. In the case of Fe2P4O12 the unit cell of this new form is with Z = 2 and two possible space groups Cc or . This dense phase exists at ordinary pressure for the zinc salt. 相似文献
18.
Evidence is presented that glycosylation of a ribose-OH group in nucleosides results in a significant downfield shift for the appended 13C nucleus and smaller upfield displacements for the adjacent carbons, providing an efficient tool for differentiating between 2′--, 3′-- and 5′--glycosyl-ribonucleosides. Therewith, the products formed on enzymatic galactosylation of uridine, inosine, and adenosine are unequivocally assigned β(1→3)-glycosidic linkages ( – ). 相似文献
19.
Hideshi Nakamura Houming Wu Junichi Kobayashi Yoichi Nakamura Yasushi Ohizumi Yoshimasa Hirata 《Tetrahedron letters》1985,26(37):4517-4520
Purealin , a novel secondary metabolite, which modurates enzymic reactions of ATPases, has been isolated from the okinawan marine sponge and the structure has been determined by the 1H-1H homonuclear and 1H-13C heteronuclear NMR chemical shift correlations and CD spectra. 相似文献
20.
1H and 13C variable temperature NMR results show that the seven-membered heterocycle exists solely in the Cea form, a situation very different from the analogous six-membered which exists predominantly in the Cee form. 相似文献