Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
Más filtros













Base de datos
Intervalo de año de publicación
1.
Inorg Chem ; 62(21): 8372-8378, 2023 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-37192407

RESUMEN

In this study, we successfully synthesized a novel A-site columnar-ordered perovskite CaZnV2O6. This compound features a square-planar-coordinated Zn2+ disorder, which is the same characteristic as the centrosymmetric paraelectric CaMnTi2O6. Unlike CaMnTi2O6, which shows a centrosymmetric paraelectric-noncentrosymmetric ferroelectric transition, CaZnV2O6 retains Pauli-paramagnetic metallicity arising from itinerant V4+ d1 electrons and centrosymmetry down to 5 K. Based on analogous compounds, we expect CaZnV2O6 to provide a new playground for the electronic and magnetic states of V4+.

2.
Materials (Basel) ; 16(5)2023 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-36903104

RESUMEN

An epitaxial film of YbFe2O4, a candidate for oxide electronic ferroelectrics, was fabricated on yttrium-stabilized zirconia (YSZ) substrate by magnetron sputtering technique. For the film, second harmonic generation (SHG), and a terahertz radiation signal were observed at room temperature, confirming a polar structure of the film. The azimuth angle dependence of SHG shows four leaves-like profiles and is almost identical to that in a bulk single crystal. Based on tensor analyses of the SHG profiles, we could reveal the polarization structure and the relationship between the film structure of YbFe2O4 and the crystal axes of the YSZ substrate. The observed terahertz pulse showed anisotropic polarization dependence consistent with the SHG measurement, and the intensity of the emitted terahertz pulse reached about 9.2% of that emitted from ZnTe, a typical nonlinear crystal, implying that YbFe2O4 can be applied as a terahertz wave generator in which the direction of the electric field can be easily switched.

3.
Inorg Chem ; 61(32): 12822-12827, 2022 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-35925759

RESUMEN

Bi0.5Pb0.5FeO3 with 1:1 mixture of Bi and Pb having charge degrees of freedom at the A-site of perovskite oxide ABO3 is obtained for the first time by high-pressure synthesis. Comprehensive synchrotron X-ray powder diffraction, optical second harmonic generation, Mössbauer spectroscopy, and hard X-ray photoemission spectroscopy measurements revealed that Bi0.5Pb0.5FeO3 is a canted antiferromagnetic insulator crystalizing in a nonpolar tetragonal I4/mcm structure with √2a × âˆš2a × 2a unit cell and has unusually Pb charge disproportionated Bi3+0.5Pb2+0.25Pb4+0.25Fe3+O3 charge distribution. The valence of transition metal M in Bi0.5Pb0.5MO3 changes from 3.5+ to 3+ and finally to 2+ from Mn to Fe and to Ni, from left to right in the periodic table as the 3d-level becomes deeper. The valences of Bi and Pb increase to compensate for the decrease in the M's valence, and Pb changes from 6s2 (2+) to 6s0 (4+) before Bi changes.

4.
Zhongguo Zhen Jiu ; 42(6): 641-6, 2022 Jun 12.
Artículo en Chino | MEDLINE | ID: mdl-35712948

RESUMEN

OBJECTIVE: To observe the effect of Buyi Pishen acupuncture (acupuncture for invigorating spleen and kidney) on inflammatory factor and synovial cartilage matrix in adjuvant arthritis (AA) rats, and to explore the mechanism of acupuncture for rheumatoid arthritis (RA). METHODS: A total of 60 clean male Wistar rats were randomized into a normal group, a model group, a tripterygium wilfordii polyglycoside tablet (TWP) group and an acupuncture group, 15 rats in each group. Rats in the model group, the TWP group and the acupuncture group received intradermal injection of Freund's complete adjuvant (FCA) at right hind foot pad to induce the AA model. TWP suspension of 8 mg/kg was given by gavage in the TWP group. Acupuncture was applied at "Shenshu" (BL 23), "Pishu" (BL 20) and right "Housanli" (ST 36), "Sanyinjiao" (SP 6), "Yanglingquan" (GB 34) in the acupuncture group, 15 min a time, once a day. The intervention was given 15 days in both TWP group and acupuncture group. The foot-pad swelling degree before modeling, before and after intervention and the arthritis index (AI) score before and after intervention were calculated; the serum levels of interleukin (IL)-1ß, IL-4, IL-10 and tumor necrosis factor-α (TNF-α) were detected by ELISA method; the ultrastructure and histomorphological changes of synovium issue were observed by transmission electron microscope and HE staining; the positive expression of matrix metalloproteinase (MMP)-3 and MMP-9 in synovium issue was detected by immunohistochemistry method. RESULTS: Before intervention, foot-pad swelling degree of the model group, the TWP group and the acupuncture group was increased compared with the normal group (P<0.01). After intervention, foot-pad swelling degree and AI score were increased compared with the normal group (P<0.01), foot-pad swelling degree and AI scores in the TWP group and the acupuncture group were lower than the model group (P<0.05), and those in the acupuncture group were decreased compared with the TWP group (P<0.05). The model group exhibited unclear nuclear membrane of synovial cells, chromatin pyknosis, massive inflammatory cell infiltration and hyperplasia in synovial tissue; the TWP group and the acupuncture group exhibited clear and smooth nuclear membrane of synovial cells, inapparent chromatin pyknosis, less inflammatory cell infiltration and hyperplasia in synovial tissue, the acupuncture group exhibited less matrix destruction as well. Compared with the normal group, serum levels of IL-1ß and TNF-α and positive expression of MMP-3 and MMP-9 in synovium issue were increased (P<0.01), while serum levels of IL-4 and IL-10 were decreased (P<0.01) in the model group. Compared with the model group, serum levels of IL-1ß and TNF-α and positive expression of MMP-3 and MMP-9 in synovium issue were decreased (P<0.05, P<0.01), while serum levels of IL-4 and IL-10 were increased (P<0.05) in the TWP group and the acupuncture group; compared with the TWP group, serum level of TNF-α and positive expression of MMP-3 and MMP-9 in synovium issue were decreased (P<0.05), while serum levels of IL-4 and IL-10 were increased (P<0.05) in the acupuncture group. CONCLUSION: Buyi Pishen acupuncture can effectively improve the injury of articular cartilage in AA rats, its mechanism maybe related to reducing the inflammatory reaction in synovium and inhibiting the degradation of articular cartilage matrix.


Asunto(s)
Terapia por Acupuntura , Artritis Experimental , Cartílago Articular , Animales , Artritis Experimental/patología , Artritis Experimental/terapia , Cromatina , Hiperplasia , Interleucina-10 , Interleucina-4 , Masculino , Metaloproteinasa 3 de la Matriz , Metaloproteinasa 9 de la Matriz , Ratas , Ratas Wistar , Factor de Necrosis Tumoral alfa/genética
5.
Zhen Ci Yan Jiu ; 46(12): 1016-22, 2021 Dec 25.
Artículo en Chino | MEDLINE | ID: mdl-34970878

RESUMEN

OBJECTIVE: To observe the effect of acupuncture of "Yinlingquan"(SP9) and "Sanyinjiao"(SP6) on expression of phosphatidylinositol-3 kinase/protein kinase B/mammalian target protein of rapamycin (PI3K/Akt/mTOR) signaling in adjuvant arthritis (AA) rats, so as to explore its mechanism underlying improvement of AA. METHODS: Forty-eight male Wistar rats were randomly divided into normal control, AA model, acupuncture and medication (tripterygium wilfordii) groups, with 12 rats in each group. The AA model was established by putting the rats in a windy, cold and wet environment for 12 h, once every day for 21 days and injection of Freund's complete adjuvant (CFA) into the sole of the right hindlimb on the 21st day. Manual acupuncture stimulation was applied at SP9 and SP6 for 30 min/time, once a day for 21 days. Rats of the medication group received gavage of tripterygium wilfordii tablets solution (8 mg/kg), once a day for 21 days, and those of the normal control group and model group received gavage of the same amount of normal saline, once a day for 21 days. The degree of joint swelling and arthritis index (AI) were detected 1 day before modeling, 3 days after modeling, and 21 days after the treatment. Twenty-four hours after the last treatment, the contents of serum cytokines interleukin (IL)-17, IL-6 and tumor necrosis factor (TNF)-α were detected by enzyme-linked immunosorbent assay (ELISA); and changes of synovial ultrastructure were observed under electron microscope. Western blot was used to detect the expression levels of PI3K, Akt, phosphorylated protein kinase B (p-Akt), phosphorylated mammalian rapamycin target protein (p-mTOR), mTOR, microtubule associated protein 1 light chain 3B (LC3-Ⅱ) and mammalian atg6 homologous protein (Beclin-1) in the synovial membrane tissue. RESULTS: Compared with the normal control group, the joint swel-ling degree and AI, contents of serum TNF-α, IL-6 and IL-17, and the expression levels of PI3K, Akt, p-Akt, mTOR and p-mTOR in the synovium were increased in the model group (P<0.05), while the expression levels of LC3-Ⅱ and Beclin-1 proteins in the synovium were significantly decreased (P<0.05). Compared with the model group, the joint swelling degree and AI, contents of serum TNF-α, IL-6 and IL-17, and the expression levels of PI3K, Akt, p-Akt, mTOR and p-mTOR were significantly decreased in the acupuncture and medication groups (P<0.05), while the expresion levels of LC3-Ⅱ and Beclin-1 proteins were significantly increased (P<0.05). Comparison between the two treatment groups showed that the therapeutic effects of acupuncture were obviously weaker than those of medication in down-regulating TNF-α and IL-6, Akt, p-Akt and mTOR levels (P<0.05) and in up-regulating Beclin-1 expression (P<0.05). Outcomes of electron microscope displayed widened nuclear membrane space, some fractured mitochondrial cristae with vacuoles, expanded rough endoplasmic reticulum, reduction of autophagosomes in the cytoplasm and ruptured synovial cell membrane in the model group, and increase of autophagosomes, deformed organelles in the acupuncture and medication groups. CONCLUSION: Acupuncture can relieve the inflammatory reactions and joint synovial injury of the affected joint in AA rats which may be associated with its effects in inhibiting PI3K/Akt/mTOR signaling and increasing the auto-phagy level of synovial cells.


Asunto(s)
Terapia por Acupuntura , Artritis Experimental , Animales , Artritis Experimental/genética , Artritis Experimental/terapia , Autofagia , Masculino , Fosfatidilinositol 3-Quinasas/genética , Proteínas Proto-Oncogénicas c-akt/genética , Ratas , Ratas Sprague-Dawley , Ratas Wistar , Serina-Treonina Quinasas TOR/genética
6.
Zhen Ci Yan Jiu ; 46(3): 194-200, 2021 Mar 25.
Artículo en Chino | MEDLINE | ID: mdl-33798291

RESUMEN

OBJECTIVE: To explore the effect of moxibustion at "Zusanli"(ST36) and "Shenshu"(BL23) on synovitis, and expressions of miR-155, Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), interlukine(IL-1) receptor-associated kinase (IRAK1), tumor necrosis factor receptor-associated factor 6 (TRAF6), nuclear factor κB (NF-κB), IL-1ß, tumor necrosis factor receptor (TNF)-α and IL-6 mRNA and protein of synovial membrane in rheumatoid arthritis (RA) rats, so as to explore its mechanism underlying improvement of RA. METHODS: A total of 48 male Wistar rats were randomly divided into normal control, model, moxibustion and antagonist groups (n=12 rats in each group). The RA model was replicated by placing the rats in a wind, cold and wet environment and injection of Freund's complete adjuvant (CFA, 0.5 mL) into the right hindlimb foot plantar. Moxibustion was applied to bilateral ST36 and BL23 for 30 min, once daily for 21 consecutive days. Rats of the antagonist group was treated by injection of TLR4 antagonist (TAK-242, 1 mg/mL, 0.1 mg/kg) via tail vein, once per day for consecutive 21 d. The joint swelling degree (JSD) and arthritis index (AI, red swelling scale) were determined, and the expression levels of various indicators of miR-155, and TLR4, myeloid MyD88, IRAK1, TRAF6, NF-κB, IL-1ß, TNF-α and IL-6 mRNA and protein were assayed by quantitative real time-PCR and Western blot, separately. RESULTS: Compared with the normal control group, the JSD and AI, and the expression levels of synovial miR-155, TLR4, MyD88, IRAK1, TRAF6, NF-κB, IL-1ß, TNF-α and IL-6 mRNA and protein were significantly increased in the model group (P<0.01). Compared with the model group, the increased levels of JSD and AI, and the expression levels of synovial miR-155, TLR4, MyD88, IRAK1, TRAF6, NF-κB, IL-1ß, TNF-α and IL-6 mRNA and protein were notably down-regulated in both moxibustion and antagonist groups (P<0.01). The effects of moxibustion were evidently superior to the antagonist in down-regulating the abovementioned indexes (P<0.01), except TLR4 mRNA and protein. CONCLUSION: Moxibustion at ST36 and BL23 can reduce the synovitis of RA rats, which is related to its effects in suppressing the expressions of miR-155, TLR4, MyD88, IRAK1, TRAF6, NF-κB, IL-1ß, TNF-α and IL-6 mRNA and protein (i.e., inhibition of miR-155/TLR4/NF-κB signaling).


Asunto(s)
Artritis Reumatoide , MicroARNs , Moxibustión , Sinovitis , Animales , Artritis Reumatoide/genética , Artritis Reumatoide/terapia , Masculino , MicroARNs/genética , FN-kappa B/genética , Ratas , Ratas Wistar , Receptor Toll-Like 4/genética
7.
Inorg Chem ; 59(16): 11749-11756, 2020 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-32799500

RESUMEN

Spontaneous polarization (Ps) of novel order-disorder type lead-free ferroelectric CaMnTi2O6 was successfully enhanced by partial V4+ substitution for Ti4+. A synchrotron X-ray diffraction study revealed that the polar displacement of octahedrally coordinated (Ti, V) in CaMn(Ti1-xVx)2O6 (0 ≤ x ≤ 0.4) increases with V4+ substitution having Jahn-Teller activity owing to the d1 electronic configuration. Our magnetic study suggested the presence of antisite disorder between Ca2+ and square planar coordinated Mn2+ associated with Mn-V intermetallic charge transfer for x ≥ 0.4, resulting in decreases in spontaneous polarization and the ferroelectric-paraelectric transition temperature. This is the first report on the enhanced polarization owing to the Jahn-Teller distortion of V4+ without stereochemical Pb2+ or Bi3+.

8.
Biophys J ; 115(12): 2295-2300, 2018 12 18.
Artículo en Inglés | MEDLINE | ID: mdl-30514634

RESUMEN

Regulation of transcription elongation is one of the key mechanisms employed to control gene expression. The single-subunit mitochondrial RNA polymerase (mtRNAP) transcribes mitochondrial genes, such as those related to ATP synthesis. We investigated how mitochondrial transcription elongation factor (TEFM) enhances mtRNAP transcription elongation using a single-molecule optical-tweezers transcription assay, which follows transcription dynamics in real time and allows the separation of pause-free elongation from transcriptional pauses. We found that TEFM enhances the stall force of mtRNAP. Although TEFM does not change the pause-free elongation rate, it enhances mtRNAP transcription elongation by reducing the frequency of long-lived pauses and shortening their durations. Furthermore, we demonstrate how mtRNAP passes through the conserved sequence block II, which is the key sequence for the switch between DNA replication and transcription in mitochondria. Our findings elucidate how both TEFM and mitochondrial genomic DNA sequences directly control the transcription elongation dynamics of mtRNAP.


Asunto(s)
ARN Polimerasas Dirigidas por ADN/metabolismo , Mitocondrias/enzimología , Factores de Transcripción/metabolismo , Transcripción Genética , Fenómenos Biomecánicos , G-Cuádruplex , Humanos , Motivos de Nucleótidos , Terminación de la Transcripción Genética
9.
Zhongguo Zhen Jiu ; 38(5): 4793-82, 2018 May 12.
Artículo en Chino | MEDLINE | ID: mdl-29797911

RESUMEN

OBJECTIVE: To observe the clinical efficacy of acupuncture combined with western medicine in the treatment of rheumatoid arthritis (RA) and its effect on blood stasis, and to explore ways to improve the clinical curative effect. METHODS: A total of 56 patients of RA were randomly divided into an observation group and a control group, 28 cases in each one. ① ibuprofen sustained-release tablets, 2 times a day, each time 0.3 g; ② methotrexate tablets (MTX), once a week, each time 10 mg ③ folic acid tablets, once a week, each time 5 mg were given in the control group, 30 days as one course, a total of 3 courses were required. In the observation group, acupuncture was adopted on the basis of the treatment as the control group. The main acupoints were Ganshu (BL 18), Pishu (BL 20), Shenshu (BL 23), Hegu (LI 4), Quchi (LI 11), Zusanli (ST 36) combined with local ashi points. The treatment was given once every day for continuous 6 days a week, the treatment for 30 days as one course, a total of 3 courses were required. The serological indexs were evaluated before and after treatment, including the rheumatoid factor (RF), hypersensitive C-reactive protein (hs-CRP), erythrocyte sedirnentation rate (ESR), platelet (PLT), fibrinogen (FBG) and D-dimer (D-D), the changes of disease activity score (DAS-28), symptom grade quantitative score, blood stasis syndrome symptom (the joint tingling, lip color, tongue, pulse, subcutaneous ecchymosis, squamous and dry skin) score were observed. RESULTS: ① The scores of RF, hs-CRP, ESR, PLT, D-D, FBG, DAS-28 and symptom grade quantitative were significantly improved in the two groups compared with those before treatment (all P<0.05), and the scores of hs-CRP, ESR, DAS-28 and symptom grading in the observation group were more better than those in the control group (all P<0.05). ② The total score of joint tingling, lip color, tongue, pulse, subcutaneous ecchymosis, squamous and dry skin and blood stasis syndrome in both groups were decreased after treatment (all P<0.05), the joint tingling, tongue, lip color and subcutaneous ecchymosis were improved obviously in the observation group than those in the control group (all P<0.05). ③ The total effective rate in the observation group was 85.7% (24/28), which was better than 75.0% (21/28) in the control group (P<0.05). CONCLUSION: Acupuncture combined with western medicine can not only improve the clinical efficacy of RA patients but also improve the blood stasis.


Asunto(s)
Terapia por Acupuntura , Artritis Reumatoide/terapia , Puntos de Acupuntura , Terapia Combinada , Ácido Fólico/uso terapéutico , Humanos , Ibuprofeno/uso terapéutico , Metotrexato/uso terapéutico , Resultado del Tratamiento
10.
Amino Acids ; 49(9): 1619-1631, 2017 09.
Artículo en Inglés | MEDLINE | ID: mdl-28664270

RESUMEN

A novel type I ribosome-inactivating protein (RIP), designated as curcin C, was purified from Jatropha curcas, an important feedback source of bio-fuel. Molecular mass and isoelectric point of curcin C were 31.398 kDa and 7.12 as detected by MALTI-TOF assay and capillary electrophoresis assay, respectively. N-terminal sequence and LC-MS/MS analyses confirmed that curcin C is a type I RIP having high homology, but not the exactly the same with curcin, another type 1 RIP isolated from the endosperm of J. curcas. It exhibited N-glycosidase activity and in vitro translation inhibition activity. Moreover, curcin C displayed a strong selectively anti-tumor activity on human cancer cells. Its cytotoxicity against osteosarcoma cell line U20S is even higher than that of Paclitaxel with IC50 of 0.019 µM. Purification and identification of curcin C not only suggested its potential in natural anticancer drug development, but also provide chance to understanding different cytotoxic action among different RIPs.


Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Cotiledón/química , Jatropha/química , Proteínas Inactivadoras de Ribosomas Tipo 1/farmacología , Secuencia de Aminoácidos , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Cotiledón/crecimiento & desarrollo , Cotiledón/metabolismo , Humanos , Concentración 50 Inhibidora , Punto Isoeléctrico , Jatropha/crecimiento & desarrollo , Jatropha/metabolismo , Peso Molecular , Osteoblastos/efectos de los fármacos , Osteoblastos/patología , Isoformas de Proteínas/química , Isoformas de Proteínas/aislamiento & purificación , Isoformas de Proteínas/farmacología , Proteínas Inactivadoras de Ribosomas Tipo 1/química , Proteínas Inactivadoras de Ribosomas Tipo 1/aislamiento & purificación
11.
Zhongguo Zhen Jiu ; 35(9): 885-8, 2015 Sep.
Artículo en Chino | MEDLINE | ID: mdl-26721137

RESUMEN

OBJECTIVE: To compare the clinical effective differences between pricking blood combined with moxibustion and west medication for acute gouty arthritis. METHODS: Forty patients with acute gouty arthritis were randomly divided into a pricking blood combined with moxibustion group (a combination group) and a western medication group, 20 cases in each one. In the combination group, pricking blood was used at the most painful points of the red turgid and painful joint once three days, total 3 times; moxibustion was applied at the same joint for 15-20 min, once a day. The moxibustion was adopted for 10 days. In the western medication group, 0. 3 g ibuprofen was prescribed orally twice a day for 10 days. The changes of uric acid (UA), high sensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR) and the joint syndrome and symptom score before and after: treatment were observed. Results In the two groups, the UA, the hs-CRP, the ESR and the joint syndrome and symptom scores were lower than those before treatment (all P<0. 05). After treatment, the UA, the ESR and the joint syndrome and symptom scores in the combination group were declined more apparently than those in the western medication group (all P<0. 05). The total effective rate in the combination group was 85. 0% (17/20) which was better than 75. 0% (15/20) in the western medication group (P<0. 05). CONCLUSION: Pricking blood combined with moxibustion could improve the joint symptoms more effectively and the effect is better than ibuprofen orally.


Asunto(s)
Artritis Gotosa/terapia , Venodisección , Moxibustión , Adolescente , Adulto , Anciano , Terapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Resultado del Tratamiento , Adulto Joven
12.
Mol Biol Rep ; 42(5): 937-45, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25433432

RESUMEN

High chilling-susceptibility is becoming the bottleneck for cultivation and commercialization of Jatropha curcas L. For insights to chilling resistance ability of this plant species, a cold response transcription factor, JcCBF2, was cloned and studied. It codes a 26 kDa protein, which contains all conserved motifs unique to the C-repeat binding factor (CBF) family and has high similarity to CBFs of Ricinus communis and Populus. Its transcripts express specifically in leaves of Jatropha at cold temperature. After transmitting the report vector, 35S::JcCBF2-GFP, into Arabidopsis thaliana, JcCBF2 protein is main detected in cell nucleus, being consistent to the nuclear orientation signal in its N-terminal. Compared to the control Arabidopsis, the frozen leaves of JcCBF2-overexpressed seedlings grow stronger with less malondialdehyde, smaller leaf conductivity and activer superoxide dismutase, showing their higher freezing tolerance. RT-PCR tests revealed that JcCBF2 functioned mainly at the early stage (0-6 h) of resistance events in Arabidopsis, and its transcripts reduced after 6 h. In addition, JcCBF2 could quickly regulate transcripts of some cold-responsive (COR) genes such as RD29A, COR105A and COR6.6, also during the early stage of frozen treatment. This study not only proves the chilling resistance roles of JcCBF2, but also presents a candidate gene engineering for improvement of chilling tolerance in J. curcas.


Asunto(s)
Aclimatación/genética , Arabidopsis/genética , Respuesta al Choque por Frío/genética , Congelación , Jatropha/genética , Proteínas de Plantas/genética , Transactivadores/genética , Secuencia de Aminoácidos , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Datos de Secuencia Molecular , Filogenia , Hojas de la Planta/genética , Hojas de la Planta/fisiología , Plantas Modificadas Genéticamente/fisiología , Plantones/genética , Plantones/fisiología , Transgenes
13.
J Org Chem ; 67(8): 2435-46, 2002 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-11950285

RESUMEN

This paper describes a new class of chiral oxazolidinone ketone catalyst for asymmetric epoxidation. High ee values have been obtained for a number of cyclic and acyclic cis-olefins. The epoxidation was stereospecific with no isomerization observed in the epoxidation of acyclic systems. Encouragingly high ee values have also been obtained for a number of terminal olefins. Mechanistic studies show that electronic interactions play an important role in stereodifferentiation.


Asunto(s)
Alquenos/química , Compuestos Epoxi/química , Compuestos Epoxi/síntesis química , Cetonas/química , Catálisis , Química Orgánica/métodos , Cromatografía Líquida de Alta Presión , Cristalografía por Rayos X , Espectroscopía de Resonancia Magnética , Conformación Molecular , Estructura Molecular , Oxidación-Reducción , Estereoisomerismo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA