排序方式: 共有37条查询结果,搜索用时 15 毫秒
1.
Reyes-Chilpa R Jiménez-Estrada M Godínez MV Hernández-Ortega S Campos M Béjar E 《Natural product letters》2002,16(4):239-242
A new cacalolide sesquiterpenoid, named as Romo-A, was isolated from the roots of Psacalium decompositum, Asteraceae, a Mexican medicinal shrub with antidiabetic properties. Its structure was elucidated by NMR, MS, IR, UV, and confirmed by X-ray diffraction studies. 相似文献
2.
Ericka Santacruz Gabriela Huelgas Sandra K. Angulo Virginia M. Mastranzo Simón Hernández-Ortega Judit A. Aviña Eusebio Juaristi Cecilia Anaya de Parrodi Patrick J. Walsh 《Tetrahedron: Asymmetry》2009,20(24):2788-2794
New chiral thioureas 1–8 containing 1,2-ethylendiamine or trans-1,2-diaminocyclohexane as the carbon skeleton, and containing an (S)-α-phenylethyl group have been prepared (79–98% yield). Thioureas 1–8 were used as ligands for the zinc-based catalyzed asymmetric hydrosilylation of acetophenone with polymethylhydrosiloxane (PMHS). The best result was achieved with monothiourea 1 (up to 75% ee), in toluene and a catalyst load of 5 mol %. 相似文献
3.
Ariel Carreño-Montero Luis A. Maldonado María Isabel Chávez Simón Hernández-Ortega Guillermo Delgado 《Tetrahedron letters》2019,60(48):151282
The synthesis of ethyl (2′-hydroxy-4′,5′-methylendioxophenyl)acetate, a fragment of the antihyperglycemic natural coumarin subcoriacin, is reported. We found an expeditious route to the title compound in five steps. Final metal catalyzed acid ethanolysis of the vinylic 1,1-methylthio methylsulfoxide derivative afforded the required aryl acetic ester, but in the absence of metal catalyst, an unexpected Pummerer rearrangement produced the 2,3-dimethylthiofuran derivative as the major product. This last result provides an alternative entry to 2,3-dimethlythiobenzofurans. 相似文献
4.
A. Casti eiras E. Bermejo L. J. Ackerman H. Beraldo J. Vald s-Martí nez S. Hern ndez-Ortega D. X. West 《Journal of Molecular Structure》1999,510(1-3):157-163
1-phenyl-1,2-propanedione bis{N(4)-methyl- and {N(4)-ethylthiosemicarbazone}, H2Pm4M and H2Pm4E, respectively, have been prepared, studied spectroscopically (1H NMR, ultraviolet and infrared) and their crystal structures solved. Intermoiety hydrogen bonding does not occur in H2Pm4M and H2Pm4E, in contrast to the analogous bis{N(4)-thiosemicarbazones} prepared from 1-phenylglyoxal. The two thiosemicarbazone moieties are on the opposite side of the carbon–carbon backbone, but the N(4)Hs intramolecularly hydrogen bond to the imine nitrogen for each moiety. 相似文献
5.
Rivero-Chan BE Marrero JG Hernández-Ortega S Mena-Rejón GJ Miranda LD 《Natural product research》2012,26(7):675-679
We describe in this article a process with which to obtain different ketones related to oleanolic and ursolic acids from a natural source, Salvia canariensis L., with minimal use of chromatography columns. Amongst the isolated compounds was 12α-bromo-3-oxo-olean-13, 28-olide (3), which was fully characterised, including a characterisation of its molecular configuration by X-ray crystallographic analysis by 1 and 2-dimensional NMR techniques. 相似文献
6.
Rubén A. Toscano Simón Hernández-Ortega Benjamín Ortiz Rubén Sánchez-Obregón Fernando Walls Francisco Yuste 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(11):1313-1315
The thermal Diels–Alder cycloadditon reaction of diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate, C16H17NO5S, with cyclopentadiene gave the pure racemates of two of the four possible diastereomers, with a complete π-facial selectivity and a high (80:20) endo/exo-sulfinyl selectivity. X-ray diffraction studies of diethyl 2-[cyano(toluene-4-sulfinyl)methylene]propanedioate and the major isomer of the cycloaddition product, namely diethyl 3-cyano-3-(toluene-4-sulfinyl)bicyclo[2.2.1]hepta-5-ene-2,2-dicarboxylate, C21H23NO5S, reveal that the conformation of the substituents on the acrylonitrile moiety produces both steric and electronic effects, which affect the stereoselectivity of the reaction. 相似文献
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8.
Douglas X. West Michelle M. Salberg Gordon A. Bain Anthony E. Liberta Jesús Valdés-Martínez Simón Hernández-Ortega 《Transition Metal Chemistry》1996,21(3):206-212
Summary Binuclear copper(II) complexes with six 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic, and 1H-and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. The crystal structure of a monomeric copper(II) complex of 5-nitrosalicylaldehyde piperidyl-thiosemicarbazone, H25NO2Sapip, grown from DMF solution, has been solved. Neither the thiosemicarbazones or their binuclear copper(II) complexes show growth inhibitory activity against Aspergillus niger, but the copper(II) complexes show some activity against the fungus Paecilomyces variotii. 相似文献
9.
Miguel-Angel Muoz-Hernndez Raymundo Cea-Olivares Simn Hernndez-Ortega 《无机化学与普通化学杂志》1996,622(8):1392-1398
The two stibocanes 1-oxa-4,6-dithia-5-stibocane diphenyldithiophosphinate O(CH2CH2S)2SbS2PPh2 1 and 1,3,6-trithia-2-stibocane diphenyldithiophosphinate S(CH2CH2S)2 · SbS2PPh2 2 were prepared from the corresponding chloro oxa- and thia-stibocanes 3 and 6 , and the ammonium salt of diphenyldithiophosphinic acid in CH2Cl2. 1 and 2 were characterized by IR, EI-MS and multinuclear NMR (1H, 13C, 31P{1H}). The crystalline state of 1 features two Sb1 ? S1 intermolecular interactions [3.987(2) Å] that results in a dimer. Alongside 1 displays both an endocyclic, transannular Sb1 ? O1 interaction [2.555(6) Å] and an exocyclic Sb1 ? S4 secondary interaction [3.327(2) Å]. The coordination geometry at the antimony could be described as AX4YE ψ-trigonal bipyramid geometry with A = Sb, X = S1, S2, S3,O1; Y = S4; S1, S2 and the lone pair lays on the equatorial plane with O1 and S4 in axial positions. The Sb1 ? S4 secondary bonding is face capping one of the planes form by the lone pair, S2 and S3 of the trigonal bipyramid. 2 also displays both an endocyclic, transannular Sb1 ? S2 interaction [2.949(3) Å] and an exocyclic Sb1 ? S5 secondary interaction [3.216(3) Å]. The antimony becomes five-coordinate, giving the AX4YE ψ-trigonal bipyramid geometry with S1, S3 and the lone pair laying on the equatorial plane with S2 and S4 in axial positions. The Sb1 ? S5 also here is face capping the plane form by the lone pair, S3 and S4 of the trigonal bipyramid. The conformation of the eight membered ring in 2 is boat-chair. In 1 the main conformation is chair-planar. Die Konformation des Achtringes in 2 ist Wanne-Sessel. In 1 ist die Konformation des Achtringes Sessel-planar. 相似文献
10.
Manuel Soriano-García Simón Hernández-Ortega Eugene Bratoeff Norma Valencia Elena Ramírez Gregoria Flores 《Journal of chemical crystallography》1998,28(6):487-491
The title compound is C29H34O4, tetragonal, P43, a = b = 10.310(1), c = 23.871(2)Å. The A, B, C, and D rings adopt envelope, half-chair, chair, and distorted chair conformations, respectively. The phenyl ring is planar. The methyl substituents at the A/B, C/D, and at C(17) are axial; and the –OCOCH3 group at C(17) and phenyl ring at C(16) are equatorial. The molecules in the crystal are held together by van der Waals forces and several C–H···O hydrogen bond interactions. 相似文献