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1.
Br J Surg ; 108(10): 1225-1235, 2021 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-34498666

RESUMO

BACKGROUND: The incidence of gastric poorly cohesive carcinoma (PCC) is increasing. The prognosis for patients with peritoneal metastases remains poor and the role of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is controversial. The aim was to clarify the impact of gastric PCC with peritoneal metastases treated by CRS with or without HIPEC. METHODS: All patients with peritoneal metastases from gastric cancer treated with CRS with or without HIPEC, in 19 French centres, between 1989 and 2014, were identified from institutional databases. Clinicopathological characteristics and outcomes were compared between PCC and non-PCC subtypes, and the possible benefit of HIPEC was assessed. RESULTS: In total, 277 patients were included (188 PCC, 89 non-PCC). HIPEC was performed in 180 of 277 patients (65 per cent), including 124 of 188 with PCC (66 per cent). Median overall survival (OS) was 14.7 (95 per cent c.i. 12.7 to 17.3) months in the PCC group versus 21.2 (14.7 to 36.4) months in the non-PCC group (P < 0.001). In multivariable analyses, PCC (hazard ratio (HR) 1.51, 95 per cent c.i. 1.01 to 2.25; P = 0.044) was associated with poorer OS, as were pN3, Peritoneal Cancer Index (PCI), and resection with a completeness of cytoreduction score of 1, whereas HIPEC was associated with improved OS (HR 0.52; P < 0.001). The benefit of CRS-HIPEC over CRS alone was consistent, irrespective of histology, with a median OS of 16.7 versus 11.3 months (HR 0.60, 0.39 to 0.92; P = 0.018) in the PCC group, and 34.5 versus 14.3 months (HR 0.43, 0.25 to 0.75; P = 0.003) in the non-PCC group. Non-PCC and HIPEC were independently associated with improved recurrence-free survival and fewer peritoneal recurrences. In patients who underwent HIPEC, PCI values of below 7 and less than 13 were predictive of OS in PCC and non-PCC populations respectively. CONCLUSION: In selected patients, CRS-HIPEC offers acceptable outcomes among those with gastric PCC and long survival for patients without PCC.


Assuntos
Procedimentos Cirúrgicos de Citorredução , Quimioterapia Intraperitoneal Hipertérmica , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Neoplasias Ovarianas/secundário , Neoplasias Peritoneais/secundário , Prognóstico , Estudos Retrospectivos , Neoplasias Gástricas/mortalidade , Neoplasias Gástricas/patologia , Adulto Jovem
2.
Benef Microbes ; 12(6): 601-612, 2021 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-34590532

RESUMO

The gut microbiota has been indicated to play a crucial role in health and disease. Apart from changes in composition between healthy individuals and those with a disease or disorder, it has become clear that also microbial activity is important for health. For instance, butyrate has been proven to be beneficial for health, because, amongst others, it is a substrate for the colonocytes, and modulates the host's immune system and metabolism. Here, we studied the effect of a blend of three mushrooms (Ganoderma lucidum GL AM P-38, Grifola frondosa GF AM P36 and Pleurotus ostreatus PO AM-GP37)) on gut microbiota composition and activity in a validated, dynamic, computer-controlled in vitro model of the colon (TIM-2). Predigested mushroom blend at three doses (0.5, 1.0 and 1.5 g/day of ingested mushroom blend) was fed to a pooled microbiota of healthy adults for 72 h, and samples were taken every day for microbiota composition (sequencing of amplicons of the V3-V4 region of the 16S rRNA gene) and activity (short-chain fatty acid (SCFA) production). The butyrate producing genera Lachnospiraceae UCG-004, Lachnoclostridium, Ruminococcaceae UCG-002 and Ruminococcaceae NK4A214-group are all dose-dependently increased when the mushroom blend was fed. Entirely in line with the increase of these butyrate-producers, the cumulative amount of butyrate also dose-dependently increased, to roughly twice the amount compared to the control (medium without mushroom blend) on the high-dose mushroom blend. Butyrate proportionally made up 53.1% of the total SCFA upon feeding the high-dose mushroom blend, compared to 27% on the control medium. In conclusion, the (polysaccharides in the) mushroom blend led to substantial increase in butyrate by the gut microbiota. These results warrant future mechanistic research on the mushroom blend, as butyrate is considered to be one of the microbial metabolites that contributes to health, by increasing barrier function and modulating inflammation.


Assuntos
Agaricales , Produtos Biológicos/farmacologia , Butiratos/metabolismo , Microbioma Gastrointestinal , Adulto , Agaricales/química , Ácidos Graxos Voláteis/biossíntese , Grifola , Humanos , Pleurotus , RNA Ribossômico 16S/genética , Reishi
3.
J Visc Surg ; 156(5): 377-379, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31466831

RESUMO

When peritoneal metastases are diagnosed (strong agreement of experts): (i) seek advice from a multidisciplinary coordination meeting (MCM) with large experience in peritoneal disease (e.g. BIG RENAPE network); (ii) transfer (or not) the patient to a referral center with experience in hyperthermic intraperitoneal chemotherapy (HIPEC), according to the advice of the MCM. With regard to systemic chemotherapy (strong agreement of experts): (i) it should be performed both before and after surgery, (ii) for no longer than 6 months; (iii) without postoperative anti-angiogenetic drugs. With regard to cytoreductive surgery (strong agreement of experts): (i) Radical surgery requires a xiphopubic midline incision; (ii) no cytoreductive surgery via laparoscopy. With regard to HIPEC: HIPEC can be proposed for trials outside an HIPEC referral center (weak agreement between experts): (i) if surgery is radical; (ii) if the expected morbidity is "reasonable"; (iii) if the indication for HIPEC was suggested by a MCM, and; (iv) mitomycin is preferred to oxaliplatin (which cannot be recommended) for this indication.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma/secundário , Quimioterapia do Câncer por Perfusão Regional/métodos , Neoplasias Colorretais/patologia , Procedimentos Cirúrgicos de Citorredução/métodos , Hipertermia Induzida/métodos , Neoplasias Peritoneais/secundário , Antineoplásicos/uso terapêutico , Carcinoma/terapia , Quimioterapia do Câncer por Perfusão Regional/normas , Terapia Combinada , Procedimentos Cirúrgicos de Citorredução/normas , Humanos , Hipertermia Induzida/normas , Neoplasias Peritoneais/terapia
4.
Eur J Cancer ; 65: 69-79, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27472649

RESUMO

PURPOSE: Diffuse malignant peritoneal mesothelioma (DMPM) is a severe disease with mainly locoregional evolution. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is the reported treatment with the longest survival. The aim of this study was to evaluate the impact of perioperative systemic chemotherapy strategies on survival and postoperative outcomes in patients with DMPM treated with curative intent with CRS-HIPEC, using a multi-institutional database: the French RENAPE network. PATIENTS AND METHODS: From 1991 to 2014, 126 DMPM patients underwent CRS-HIPEC at 20 tertiary centres. The population was divided into four groups according to perioperative treatment: only neoadjuvant chemotherapy (NA), only adjuvant chemotherapy (ADJ), perioperative chemotherapy (PO) and no chemotherapy before or after CRS-HIPEC (NoC). RESULTS: All groups (NA: n = 42; ADJ: n = 16; PO: n = 16; NoC: n = 48) were comparable regarding clinicopathological data and main DMPM prognostic factors. After a median follow-up of 61 months, the 5-year overall survival (OS) was 40%, 67%, 62% and 56% in NA, ADJ, PO and NoC groups, respectively (P = 0.049). Major complications occurred for 41%, 45%, 35% and 41% of patients from NA, ADJ, PO and NoC groups, respectively (P = 0.299). In multivariate analysis, NA was independently associated with worse OS (hazard ratio, 2.30; 95% confidence interval, 1.07-4.94; P = 0.033). CONCLUSION: This retrospective study suggests that adjuvant chemotherapy may delay recurrence and improve survival and that NA may impact negatively the survival for patients with DMPM who underwent CRS-HIPEC with curative intent. Upfront CRS and HIPEC should be considered when achievable, waiting for stronger level of scientific evidence.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Procedimentos Cirúrgicos de Citorredução , Hipertermia Induzida , Neoplasias Pulmonares/terapia , Mesotelioma/terapia , Neoplasias Peritoneais/terapia , Adolescente , Adulto , Idoso , Quimioterapia Adjuvante , Procedimentos Cirúrgicos de Citorredução/métodos , Feminino , Humanos , Injeções Intraperitoneais , Neoplasias Pulmonares/mortalidade , Masculino , Mesotelioma/mortalidade , Mesotelioma Maligno , Pessoa de Meia-Idade , Neoplasias Peritoneais/mortalidade , Estudos Retrospectivos , Análise de Sobrevida , Adulto Jovem
5.
Ann Surg Oncol ; 23(6): 1971-9, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26753751

RESUMO

BACKGROUND: Peritoneal carcinomatosis is an increasingly common finding in gastric carcinoma. Previously, patients were treated as terminal, and median survival was poor. The use of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in this context is still highly debatable. OBJECTIVE: The aim of this study was to evaluate the long-term outcomes associated with CRS and HIPEC, and define prognostic factors for cure, if possible. PATIENTS AND METHODS: All patients with gastric carcinomatosis from five French institutions who underwent combined complete CRS and HIPEC and had a minimum follow-up of 5 years were included in this study. Cure was defined as a disease-free interval of more than 5 years from the last treatment until the last follow-up. RESULTS: Of the 81 patients who underwent CRS and HIPEC from 1989 to 2009, 59 had a completeness of cytoreduction score (CCS) of 0 (complete macroscopic resection), and the median Peritoneal Cancer Index (PCI) score was 6. Mitomycin C was the most commonly used drug during HIPEC (88 %). The 5-year overall survival (OS) rate was 18 %, with nine patients still disease-free at 5 years, for a cure rate of 11 %. All 'cured' patients had a PCI score below 7 and a CCS of 0. Factors associated with improved OS on multivariate analysis were synchronous resection (p = 0.02), a lower PCI score (p = 0.12), and the CCS (p = 0.09). CONCLUSION: The cure rate of 11 % for patients with gastric carcinomatosis who are deemed terminal emphasizes that CRS and HIPEC should be considered in highly selected patients (low disease extent and complete CRS).


Assuntos
Adenocarcinoma/terapia , Carcinoma/terapia , Quimioterapia do Câncer por Perfusão Regional , Procedimentos Cirúrgicos de Citorredução , Hipertermia Induzida , Neoplasias Peritoneais/terapia , Neoplasias Gástricas/terapia , Adenocarcinoma/patologia , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma/patologia , Terapia Combinada , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Peritoneais/secundário , Prognóstico , Neoplasias Gástricas/patologia , Taxa de Sobrevida , Adulto Jovem
6.
Dalton Trans ; 44(46): 20207-15, 2015 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-26537572

RESUMO

High-spin square-planar molecular compounds are rare. In an effort to access this unique combination of geometry and spin state, we report the synthesis of a series of M(II) compounds stabilized by a trianionic pincer-type ligand, highlighting the formation of a high-spin square-planar Co(II) complex. Low-temperature, variable-frequency EPR measurements reveal that the ground electronic state of the Co(II) analogue is a highly anisotropic Kramers doublet (effective g values 7.35, 2.51, 1.48). This doublet can be identified with the lowest doublet of a quartet, S = 3/2 spin state that exhibits a very large ZFS, D ≥ 50 cm(-1). The observation of an effective g value considerably greater than the largest spin-only value 6, demonstrates that the orbital angular moment is essentially unquenched along one spatial direction. Density Functional Theory (DFT) and time-dependent DFT calculations reveal the electronic configurations of the ground and excited orbital states. A qualitative crystal field description of the geff tensor shows that it originates from the spin-orbit coupling acting on states obtained through the transfer of a ß electron from the doubly occupied xy to the singly-occupied {xz/yz} orbitals.


Assuntos
Cobalto/química , Complexos de Coordenação/química , Ânions/química , Complexos de Coordenação/síntese química , Espectroscopia de Ressonância de Spin Eletrônica , Elétrons , Ligantes , Modelos Moleculares , Teoria Quântica
7.
Eur J Surg Oncol ; 41(10): 1361-7, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26263848

RESUMO

BACKGROUND: Over the last two decades, many surgical teams have developed programs to treat peritoneal carcinomatosis with extensive cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC). Currently, there are no specific recommendations for HIPEC procedures concerning environmental contamination risk management, personal protective equipment (PPE), or occupational health supervision. METHODS: A survey of the institutional practices among all French teams currently performing HIPEC procedures was carried out via the French network for the treatment of rare peritoneal malignancies (RENAPE). RESULTS: Thirty three surgical teams responded, 14 (42.4%) which reported more than 10 years of HIPEC experience. Some practices were widespread, such as using HIPEC machine approved by the European Community (100%), individualized or centralized smoke evacuation (81.8%), "open" abdominal coverage during perfusion (75.8%), and maintaining the same surgeon throughout the procedure (69.7%). Others were more heterogeneous, including laminar flow air circulation (54.5%) and the provision of safety protocols in the event of perfusate spills (51.5%). The use of specialized personal protective equipment is ubiquitous (93.9%) but widely variable between programs. CONCLUSION: Protocols regarding cytoreductive surgery/HIPEC and the associated professional risks in France lack standardization and should be established.


Assuntos
Ar Condicionado/métodos , Antineoplásicos/uso terapêutico , Carcinoma/terapia , Procedimentos Cirúrgicos de Citorredução/métodos , Hipertermia Induzida/métodos , Infusões Parenterais/métodos , Neoplasias Peritoneais/terapia , Equipamento de Proteção Individual/estatística & dados numéricos , Padrões de Prática Médica , França , Humanos , Saúde Ocupacional , Gestão de Riscos , Fumaça , Inquéritos e Questionários
8.
Chem Sci ; 6(1): 608-612, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-28706628

RESUMO

Square-planar high-spin Fe(ii) molecular compounds are rare and the only three non-macrocyclic or sterically-driven examples reported share a common FeO4 core. Using an easily modifiable pincer-type ligand, the successful synthesis of the first compound of this type that breaks the FeO4 motif was achieved. In addition, we present the first evidence that geometry and spin state persist in solution. Extensive characterization includes the first high-field EPR and variable field/temperature Mössbauer spectra for this class of compounds. Analysis of the spectroscopic data indicates this complex exhibits a large and positive zero-field splitting tensor. Furthermore, the unusually small ΔEQ value determined for this compound is rationalized on the basis of DFT calculations.

9.
Ann Fr Anesth Reanim ; 33(12): 696-9, 2014 Dec.
Artigo em Francês | MEDLINE | ID: mdl-25447780

RESUMO

The diagnosis of perioperative vertebral artery dissection can be difficult because of non-specific clinical signs. We report a case revealed by a tegmento-thalamic stroke after an abdominal second surgical look. The interest of this observation is related to a particular evolution in two steps separated by a 2-month-interval and an intercurrent cervical manipulation. After the second anesthesia, neck pain associated with a third cranial nerve palsy and a supranuclear ophtalmoplegia revealed a tegmento-thalamic ischemic stroke due to vertebral artery dissection. We discuss here the different factors possibly involved in the pathophysiology of postoperative vertebral artery dissection: positioning, cervical manipulation, subclavian central venous access and cisplatin toxicity. Vertebral artery dissection should be discussed in case of postoperative neck pain, especially with non-typical symptomatology.


Assuntos
Complicações Pós-Operatórias/diagnóstico , Dissecação da Artéria Vertebral/diagnóstico , Antineoplásicos/uso terapêutico , Neoplasias do Apêndice/complicações , Neoplasias do Apêndice/cirurgia , Isquemia Encefálica/etiologia , Isquemia Encefálica/terapia , Cisplatino/efeitos adversos , Cisplatino/uso terapêutico , Progressão da Doença , Feminino , Humanos , Manipulação da Coluna , Pessoa de Meia-Idade , Cervicalgia/etiologia , Cervicalgia/terapia , Doenças do Nervo Oculomotor/etiologia , Doenças do Nervo Oculomotor/terapia , Complicações Pós-Operatórias/terapia , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/terapia , Paralisia Supranuclear Progressiva/etiologia , Paralisia Supranuclear Progressiva/terapia , Dissecação da Artéria Vertebral/terapia
10.
Eur J Surg Oncol ; 39(12): 1435-43, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24209430

RESUMO

BACKGROUND: Despite a high response rate to front-line therapy, prognosis of epithelial ovarian carcinoma (EOC) remains poor. Approaches that combine Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) have been developed recently. The purpose of this study was to assess early and long-term survival in patients treated with this strategy. PATIENTS AND METHODS: A retrospective cohort multicentric study from French centres was performed. All consecutive patients with advanced and recurrent EOC treated with CRS and HIPEC were included. RESULTS: The study included 566 patients from 13 centres who underwent 607 procedures between 1991 and 2010. There were 92 patients with advanced EOC (first-line treatment), and 474 patients with recurrent EOC. A complete cytoreductive surgery was performed in 74.9% of patients. Mortality and grades 3 to 4 morbidity rates were 0.8% and 31.3%, respectively. The median overall survivals were 35.4 months and 45.7 months for advanced and recurrent EOC, respectively. There was no significant difference in overall survival between patients with chemosensitive and with chemoresistant recurrence. Peritoneal Cancer Index (PCI) that evaluated disease extent was the strongest independent prognostic factor for overall and disease-free survival in all groups. CONCLUSION: For advanced and recurrent EOC, curative therapeutic approach combining optimal CRS and HIPEC should be considered as it may achieve long-term survival in patients with a severe prognosis disease, even in patients with chemoresistant disease. PCI should be used for patient's selection.


Assuntos
Antineoplásicos/administração & dosagem , Carcinoma/tratamento farmacológico , Carcinoma/cirurgia , Quimioterapia do Câncer por Perfusão Regional , Neoplasias Ovarianas/patologia , Neoplasias Peritoneais/tratamento farmacológico , Neoplasias Peritoneais/cirurgia , Adulto , Idoso , Antineoplásicos/uso terapêutico , Carcinoma/secundário , Quimioterapia do Câncer por Perfusão Regional/efeitos adversos , Fístula do Sistema Digestório/etiologia , Intervalo Livre de Doença , Feminino , França , Humanos , Hipertermia Induzida , Estimativa de Kaplan-Meier , Leucopenia/induzido quimicamente , Pessoa de Meia-Idade , Neoplasias Peritoneais/secundário , Hemorragia Pós-Operatória/etiologia , Modelos de Riscos Proporcionais , Insuficiência Renal/etiologia , Estudos Retrospectivos , Taxa de Sobrevida
12.
Am J Physiol Heart Circ Physiol ; 297(2): H836-45, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19542492

RESUMO

The aims of this study were to study the influence of the duration of diabetes, the role of endothelial-derived vasodilators, and the role of phosphodiesterase (PDE) isoform activity in the early changes in vascular reactivity of aortic rings from diabetic rats. Diabetes mellitus was induced in female rats by intravenous streptozotocin (85 mg/kg). Two or 4 wk later, thoracic aortic rings from control and diabetic rats were isolated, and vascular responses to acetylcholine (ACh), S-nitroso-N-acetylpenicillamine (SNAP) [nitric oxide (NO) donor], DMPPO (PDE5 inhibitor), and phenylephrine (PE) were obtained in the presence and absence of endothelium or other drugs. PDE isoform activity was also measured. At 2 wk, responses to ACh and DMPPO were enhanced, whereas those to PE were attenuated in diabetic rats relative to controls. Indomethacin and SQ-29548 (a thromboxane A(2) receptor antagonist), but not N(G)-nitro-L-arginine methyl ester, corrected these differences. The responses to SNAP, and cAMP and cGMP hydrolytic activities, were similar in the two groups. In contrast, at 4 wk, ACh, DMPPO, and PE produced similar responses in the two groups: N(G)-nitro-L-arginine methyl ester rendered the response to PE lower in the diabetic group, and this was corrected by indomethacin, but not SQ-29548, treatment. The response to SNAP was greater in the diabetic group, and this was corrected by DMPPO. Activity of all PDEs was decreased at 4 wk. We conclude that, at 2 wk, there is modulation of thromboxane A(2) production, but no change in the NO system or PDE isoform activities. At 4 wk, a reduction in NO activity is superimposed; at this stage, PDE activity is reduced, together with increased production of vasodilating prostaglandins, possibly as a compensatory mechanism to maintain normal vascular reactivity.


Assuntos
Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/fisiopatologia , Endotélio Vascular/enzimologia , Diester Fosfórico Hidrolases/metabolismo , Acetilcolina/farmacologia , Alopurinol/análogos & derivados , Alopurinol/farmacologia , Animais , Aorta Torácica/enzimologia , Aorta Torácica/fisiopatologia , Glicemia/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 1/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 2/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 3/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/fisiopatologia , Modelos Animais de Doenças , Endotélio Vascular/efeitos dos fármacos , Feminino , Doadores de Óxido Nítrico/farmacologia , Fenilefrina/farmacologia , Ratos , Ratos Sprague-Dawley , S-Nitroso-N-Acetilpenicilamina/farmacologia , Vasoconstrição/efeitos dos fármacos , Vasoconstrição/fisiologia , Vasoconstritores/farmacologia , Vasodilatação/efeitos dos fármacos , Vasodilatação/fisiologia , Vasodilatadores/farmacologia
14.
J Org Chem ; 67(1): 72-8, 2002 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-11777441

RESUMO

The presence of catalytic amounts of CeCl(3) improves yields and simplifies procedure in the Reformatsky reactions of ethyl bromofluoroacetate with aldehydes and ketones to generate diastereomeric mixtures of alpha-fluoro-beta-hydroxy esters, some of which can be separated by crystallization or column flash chromatography. Diastereomerically pure alpha-fluoro-beta-hydroxy acids are obtained by mild alkaline hydrolysis of the resolved alpha-fluoro-beta-hydroxy esters. Detailed NMR data of new alpha-fluoro-beta-hydroxy esters and alpha-fluoro-beta-hydroxy acids are also presented.

15.
Acta Crystallogr C ; 57(Pt 12): 1408-9, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11740099

RESUMO

The titanium metal center in the title compound, [Ti(C19H27NSi)(C16H14)], is coordinated in a distorted tetrahedral geometry by a eta5-indenyl ligand, a dimethylsilyl-bridged N-cyclobutylamido ligand and an s-cis-eta4-1,4-diphenyl-1,3-butadiene ligand in a 'prone' pi-fashion, revealing a formal divalent Ti center.

16.
J Org Chem ; 66(22): 7443-8, 2001 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-11681959

RESUMO

The total synthesis of asteriscanolide (1) has been achieved by taking advantage on an intermolecular Pauson-Khand cycloaddition and a ring-closing metathesis as key bond-forming transformations. The approach incorporates the cyclooctane stereogenic center prior to ring formation. Interestingly, the ring-closing metathesis generates a new eight-membered ring with an "in-out" intrabridgehead relationship.


Assuntos
Ciclo-Octanos , Cetonas/síntese química , Sesquiterpenos/síntese química , Ciclização , Lactonas/síntese química
17.
J Org Chem ; 66(21): 7055-8, 2001 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-11597229

RESUMO

The synthesis and characterization of both diastereomers of a system comprised of two [2.2]paracyclophane units linked through a single 4,4' bond are described. Both the meso and d,l diastereomers of 4,4'-bis(octafluoro[2.2]paracyclophane) have been prepared via a palladium-catalyzed reductive homocoupling reaction by copper, producing a 3:2 ratio of meso and d,l diastereomers. A similar reductive homocoupling of pseudo-o-iodotrifluoromethyloctafluoro[2.2]paracyclophane gave only the analogous meso diastereomer. Single-crystal X-ray structures were obtained for all of the diparacyclophane products.

18.
Acta Crystallogr C ; 57(Pt 9): 1027-9, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11588359

RESUMO

The one-dimensional chain catena-poly[[aqua(2,2':6',2"-terpyridyl-kappa(3)N)nickel(II)]-mu-cyano-kappa(2)N:C-[bis(cyano-kappaC)nickelate(II)]-mu-cyano-kappa(2)C:N], [Ni(terpy)(H(2)O)]-trans-[Ni-mu-(CN)(2)-(CN)(2)](n) or [Ni(2)(CN)(4)(C(15)H(11)N(3))(H(2)O)], consists of infinite linear chains along the crystallographic [10-1] direction. The chains are composed of two distinct types of nickel ions, paramagnetic octahedral [Ni(terpy)(H(2)O)](2+) cations (with twofold crystallographic symmetry) and diamagnetic planar [Ni(CN)(4)](2-) anions (with the Ni atom on an inversion center). The [Ni(CN)(4)](2-) units act as bidentate ligands bridging through two trans cyano groups thus giving rise to a new example of a trans-trans chain among planar tetracyanonickelate complexes. The coordination geometry of the planar nickel unit is typical of slightly distorted octahedral nickel(II) complexes, but for the [Ni(CN)(4)](2-) units, the geometry deviates from a planar configuration due to steric interactions with the terpyridine ligands.

19.
Inorg Chem ; 40(20): 5077-82, 2001 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-11559063

RESUMO

Addition of 2 equiv of a sigma-donor ligand (L = pyridine, 4-picoline, or quinoline) to complexes of the type [W(NPh)(eta(4)-arene)(o-(Me3SiN)2C6H4)] (arene = CH3CH2C6H5 (3), CH3CH2CH2C6H5 (4)) gave the W(IV)L2 compounds, [W(NPh)(o-(Me3SiN)2C6H4)(C5H5N)2] (5), [W(NPh)(o-(Me3SiN)2C6H4)(p-C6H7N)2] (6), and [W(NPh)(o-(Me3SiN)2C6H4)(C9H7N)2] (7). Synthesis of compounds 5 and 6 by Na degrees reduction of [W(NPh)(o-(Me3SiN)2C6H4)Cl2] in the presence of 3 equiv of L (L = 5, pyridine or 6, 4-picoline) is also presented. Compounds 5, 6, and 7 display hindered rotation of the donor ligands about the W-N bonds, resulting from a steric interaction with the Me3Si groups of the diamide ligand. The coordinative unsaturation of 5 and 6 has also been explored. Compounds 5 and 6 readily react with either CO and PMe3 to generated the six coordinate complexes [W(NPh)(o-(Me3SiN)2C6H4)(C5H5N)2(CO)] (8a), [W(NPh)(o-(Me3SiN)2C6H4)(C6H7N)2(CO)] (8b), [W(NPh)(o-(Me3SiN)2C6H4)(C5H5N)(PMe3)2] (10a), and [W(NPh)(o-(Me3SiN)2C6H4)(C6H7N)(PMe3)2] (10b), respectively.

20.
J Org Chem ; 66(19): 6381-8, 2001 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-11559190

RESUMO

Fluorine-containing derivatives of amino acids are assuming increasing importance as probes of biological function and enzyme mechanism. We now report a new, flexible route to enantiomerically pure L-4,4-difluoroglutamic acid that exploits the addition of difluorinated nucleophiles to configurationally stable alpha-aminoaldehydes. Conversion of the difluorinated adducts to L-4,4-difluoroglutamic acid can be accomplished in three steps by Barton-McCombie dehydroxylation and acid hydrolysis.


Assuntos
Aldeídos/química , Glutamatos/síntese química , Aspartato-Amônia Ligase/química , Aspartato-Amônia Ligase/metabolismo , Glutamatos/química , Glutamatos/metabolismo , Hidrólise , Hidroxilação , Conformação Molecular
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