Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 125
Filtrar
1.
Proc Natl Acad Sci U S A ; 118(12)2021 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-33737391

RESUMO

Kleine-Levin syndrome (KLS) is a rare disorder characterized by severe episodic hypersomnia, with cognitive impairment accompanied by apathy or disinhibition. Pathophysiology is unknown, although imaging studies indicate decreased activity in hypothalamic/thalamic areas during episodes. Familial occurrence is increased, and risk is associated with reports of a difficult birth. We conducted a worldwide case-control genome-wide association study in 673 KLS cases collected over 14 y, and ethnically matched 15,341 control individuals. We found a strong genome-wide significant association (rs71947865, Odds Ratio [OR] = 1.48, P = 8.6 × 10-9) within the 3'region of TRANK1 gene locus, previously associated with bipolar disorder and schizophrenia. Strikingly, KLS cases with rs71947865 variant had significantly increased reports of a difficult birth. As perinatal outcomes have dramatically improved over the last 40 y, we further stratified our sample by birth years and found that recent cases had a significantly reduced rs71947865 association. While the rs71947865 association did not replicate in the entire follow-up sample of 171 KLS cases, rs71947865 was significantly associated with KLS in the subset follow-up sample of 59 KLS cases who reported birth difficulties (OR = 1.54, P = 0.01). Genetic liability of KLS as explained by polygenic risk scores was increased (pseudo R2 = 0.15; P < 2.0 × 10-22 at P = 0.5 threshold) in the follow-up sample. Pathway analysis of genetic associations identified enrichment of circadian regulation pathway genes in KLS cases. Our results suggest links between KLS, circadian regulation, and bipolar disorder, and indicate that the TRANK1 polymorphisms in conjunction with reported birth difficulties may predispose to KLS.


Assuntos
Citocinas/genética , Suscetibilidade a Doenças , Variação Genética , Síndrome de Kleine-Levin/complicações , Síndrome de Kleine-Levin/genética , Complicações do Trabalho de Parto/epidemiologia , Complicações do Trabalho de Parto/etiologia , Transtorno Bipolar/etiologia , Distúrbios do Sono por Sonolência Excessiva/etiologia , Feminino , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Síndrome de Kleine-Levin/epidemiologia , Masculino , Razão de Chances , Polimorfismo Genético , Gravidez , Medição de Risco , Fatores de Risco
2.
Angew Chem Int Ed Engl ; 63(43): e202411232, 2024 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-39056890

RESUMO

Cu-catalyzed asymmetric allylic borylation of 3,3'-disubstituted 1-vinylcyclobutan-1-ols renders axially chiral allylborane systems, with high asymmetric induction for both enantiomers, by precise selection of the cis or trans substrate. The enantioenriched alkylidenecyclobutanes served as chiral platform to prove the conceptually challenging transference of the axial-to-point chirality through two new stereocenters and one pseudoasymmetric carbon generated via diastereoconvergent allylation of aldehydes, without enantioselective erosion.

3.
Angew Chem Int Ed Engl ; 62(22): e202302416, 2023 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-37042431

RESUMO

We have demonstrated that the catalytic and enantioselective vinylcyclopropane-cyclopentene rearrangement can be carried out on (vinylcyclopropyl)acetaldehydes through activation via enamine intermediates. The reaction makes use of racemic starting materials that, upon ring opening facilitated by the catalytic generation of a donor-acceptor cyclopropane, deliver an acyclic iminium ion/dienolate intermediate in which all stereochemical information has been deleted. The final cyclization step forms the rearrangement product, showing that chirality transfer from the catalyst to the final compound is highly effective and leads to the stereocontrolled formation of a variety of structurally different cyclopentenes.

4.
Beilstein J Org Chem ; 19: 477-486, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37123091

RESUMO

The contribution to the energy barrier of a series of tethers in transannular cycloadditions of cycloalkenes with hydrazones has been computationally studied by using DFT. The Houk's distortion model has been employed to evaluate the influence of the tether in the cycloaddition reaction. That model has been extended to determine the contribution of each tether and, more importantly, the effect exerted between them. In addition to the distortion induced by the tethers, the entropy effects caused by them has also been studied. The analysis of the evolution of the electron localization function along the reaction revealed the highly concerted character of the reaction.

5.
Immunology ; 165(2): 234-249, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34775592

RESUMO

COVID-19 disease is the manifestation of syndrome coronavirus 2 (SARS-CoV-2) infection, which is causing a worldwide pandemic. This disease can lead to multiple and different symptoms, being lymphopenia associated with severity one of the most persistent. Natural killer cells (NK cells) are part of the innate immune system, being fighting against virus-infected cells one of their key roles. In this study, we determined the phenotype of NK cells after COVID-19 and the main characteristic of SARS-CoV-2-specific-like NK population in the blood of convalescent donors. CD57+ NKG2C+ phenotype in SARS-CoV-2 convalescent donors indicates the presence of 'memory'/activated NK cells as it has been shown for cytomegalovirus infections. Although the existence of this population is donor dependent, its expression may be crucial for the specific response against SARS-CoV-2, so that, it gives us a tool for selecting the best donors to produce off-the-shelf living drug for cell therapy to treat COVID-19 patients under the RELEASE clinical trial (NCT04578210).


Assuntos
Transferência Adotiva , Doadores de Sangue , COVID-19/imunologia , Convalescença , Memória Imunológica , Células Matadoras Naturais/imunologia , SARS-CoV-2/imunologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
6.
Chemistry ; 28(62): e202202267, 2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36111677

RESUMO

We have studied the enantioselective transannular aminohalogenation reaction of unsaturated medium-sized cyclic benzosulfonamides by using both chiral Brønsted acid and phase-transfer catalysis. Under optimized conditions, a variety of bicyclic adducts can be obtained with good yields and high enantioselectivities. The mechanism of the reaction was also studied by using computational tools; we observed that the reaction involves the participation of a conformer of the nine-membered cyclic substrate with planar chirality in which the stereochemical outcome is controlled by the relative reactivity of the two pseudorotational enantiomers when interacting with the chiral catalyst.


Assuntos
Ácidos , Estereoisomerismo , Catálise
7.
J Org Chem ; 87(1): 693-707, 2022 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-34928602

RESUMO

The catalyzed desymmetrizative ring expansion of alkenylcyclobutanols promoted by halofunctionalization of the alkene moiety with N-bromosuccinimide has been experimentally and computationally studied. The reaction yields highly enantioenriched cyclopentanones bearing two all-carbon quaternary stereocenters, one of them being generated in the rearrangement of the cyclobutane ring and the other by enantioselective desymmetrization. The reaction is competitive with the formation of a spiroepoxide, but it turns completely selective toward the cyclopentanone when a chiral bisphosphonium magnesium salt is employed as a catalyst. Mechanistic studies support the formation of an ion pair leading to a complex with only a unit of phosphoric acid, which is the resting state of the catalytic cycle. Calculations reproduce in an excellent way the observed reactivity and predict the effect exerted by the substituents of the aromatic ring linked to the double bond. The computational studies also revealed the reaction as a highly asynchronous concerted process taking place as one kinetic step but in two stages: (i) halogenation of the double bond and (ii) rearrangement of the cyclobutane. No intermediates are present in the reaction as energy minima. The experimental scope of the reaction further confirms the predictions for the observed reactivity and selectivity.

8.
J Org Chem ; 87(15): 10062-10072, 2022 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-35880953

RESUMO

A transannular approach has been developed for the construction of pyrrolo[1,2-b]isoquinolinones starting from benzo-fused nine-membered enelactams. This process takes place in the presence of a halogenating agent and under Brønsted acid catalysis and proceeds via a transannular amidohalogenation, followed by elimination. The reaction has been found to be wide in scope, enabling the formation of a variety of tricyclic products in good overall yield, regardless of the substitution pattern in the initial lactam substrate. The reaction has also been applied to the total synthesis of a reported topoisomerase I inhibitor and to the formal synthesis of rosettacin. Further extension of this methodology allows the preparation of 10-iodopyrrolo[1,2-b]isoquinolinones by using an excess of halogenating agent and these compounds can be further manipulated through standard Suzuki coupling chemistry into a variety of 10-aryl-substituted pyrrolo[1,2-b]isoquinolinones.


Assuntos
Catálise
9.
Phys Chem Chem Phys ; 24(22): 14072-14084, 2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35640548

RESUMO

We present a detailed theoretical survey of the electronic structure of excited states of the CO2 molecule, with the aim of providing a well-defined theoretical framework for the quantum dynamical studies at energies beyond 12 eV from the ground state. One of the major goals of our work is to emphasize the need for dealing with the presence of both molecular valence and Rydberg states. Although a CASSCF/MRCI approach can be used to appropriately describe the lowest-lying valence states, it becomes incapable of describing the upper electronic states due to the exceedingly large number of electronic excitations required. To circumvent this we employ instead the EOM-CCSD monoconfigurational method to describe the manifold of both valence and Rydberg states in the Franck-Condon region and then a matching procedure to connect these EOM-CCSD eigensolutions with those obtained from CASSCF/MRCI in the outer region, thus ensuring the correct asymptotic behavior. Within this hybrid level of theory, we then analyze the role of valence and Rydberg states in the dynamical mechanism of the photodissociation of quasi-linear CO2 into CO + O fragments, by considering a simple but effective 1D multistate non-adiabatic model for the ultrafast C-O bond break up. We show evidence that the metastability of the Rydberg states must be accounted for in the ultrafast dynamics since they produce changes in the photodissociation yields within the first tens of fs.

10.
Eur J Haematol ; 106(2): 196-204, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33084101

RESUMO

OBJECTIVE: Describe the GETH haploidentical stem cell transplantation (haplo-HSCT) activity in non-malignant disease (NMDs). METHODS: We retrospectively analyzed data from children with NMDs who underwent haplo-HSCT. RESULTS: From January 2001 to December 2016, 26 pediatric patients underwent 31 haplo-HSCT through ex vivo T cell-depleted (TCD) graft platforms or post-transplantation cyclophosphamide (PT-Cy) at 7 Spanish centers. Five cases employed unmanipulated PT-Cy haplo-HSCT, 16 employed highly purified CD34+ cells, and 10 employed ex vivo TCD grafts manipulated either with CD3+ CD19+ depletion, TCRαß+ CD19+ selection or naive CD45RA+ T-cell depletion. Peripheral blood stem cells were the sole source for patients following TCD haplo-HSCT, and bone marrow was the source for one PT-Cy haplo-HSCT. The most common indications for transplantation were primary immunodeficiency disorders (PIDs), severe aplastic anemia, osteopetrosis, and thalassemia. The 1-year cumulative incidence of graft failure was 27.4%. The 1-year III-IV acute graft-versus-host disease (GvHD) and 1-year chronic GvHD rates were 34.6% and 16.7%, respectively. The 2-year overall survival was 44.9% for PIDs, and the 2-year graft-versus-host disease-free and relapse-free survival rate was 37.6% for the other NMDs. The transplantation-related mortality at day 100 was 30.8%. CONCLUSION: Although these results are discouraging, improvements will come if procedures are centralized in centers of expertise.


Assuntos
Transplante de Células-Tronco Hematopoéticas/estatística & dados numéricos , Transplante Haploidêntico/estatística & dados numéricos , Fatores Etários , Pré-Escolar , Gerenciamento Clínico , Feminino , Sobrevivência de Enxerto , Doença Enxerto-Hospedeiro/diagnóstico , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Transplante de Células-Tronco Hematopoéticas/métodos , Humanos , Lactente , Infecções/etiologia , Infecções/terapia , Masculino , Avaliação de Resultados em Cuidados de Saúde , Pediatria/métodos , Padrões de Prática Médica , Prognóstico , Estudos Retrospectivos , Espanha , Quimeras de Transplante , Condicionamento Pré-Transplante , Transplante Haploidêntico/efeitos adversos , Transplante Haploidêntico/métodos
11.
Org Biomol Chem ; 19(17): 3763-3775, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33949549

RESUMO

The 8-azabicyclo[3.2.1]octane scaffold is the central core of the family of tropane alkaloids, which display a wide array of interesting biological activities. As a consequence, research directed towards the preparation of this basic structure in a stereoselective manner has attracted attention from many research groups worldwide across the years. Despite this, most of the approaches rely on the enantioselective construction of an acyclic starting material that contains all the required stereochemical information to allow the stereocontrolled formation of the bicyclic scaffold. As an alternative, there are a number of important methodologies reported in which the stereochemical control is achieved directly in the same transformation that generates the 8-azabicyclo[3.2.1]octane architecture or in a desymmetrization process starting from achiral tropinone derivatives. This review compiles the most relevant achievements in these areas.

12.
Angew Chem Int Ed Engl ; 59(5): 2100-2104, 2020 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-31730740

RESUMO

Medium-sized carbocycles containing an α,ß-unsaturated ketone moiety as Michael acceptor site and a ketone moiety as internal electrophilic site are ideal substrates to conduct Cu(I)-catalyzed conjugated borylation followed by electrophilic intramolecular trapping that results into a pioneer transannular borylative ring closing reaction. The relative configuration of three adjacent stereocenters is controlled, giving access to a single diastereoisomer for a wide range of substrates tested. Moreover, when a chiral ligand is incorporated, the reaction provides enantioenriched polycyclic products with up to 99 % ee.

13.
Angew Chem Int Ed Engl ; 59(17): 6780-6784, 2020 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-32039546

RESUMO

The enantioselective synthesis of tropanols has been accomplished through chiral phosphoric acid catalyzed pseudotransannular ring opening of 1-aminocyclohept-4-ene-derived epoxides. The reaction proceeds together with the desymmetrization of the starting material and leads to the direct formation of the 8-azabicyclo[3.2.1]octane scaffold with excellent stereoselectivity. The synthetic applicability of the reaction was demonstrated by the enantioselective synthesis of the two natural products (-)-α-tropanol and (+)-ferruginine.


Assuntos
Tropanos/química , Tropanos/síntese química , Alcenos/química , Catálise , Técnicas de Química Sintética , Concentração de Íons de Hidrogênio , Estereoisomerismo
14.
J Am Chem Soc ; 141(24): 9495-9499, 2019 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-31140796

RESUMO

Catalytic and enantioselective approaches to transannular reactions are very limited and mostly are based on chiral Lewis acid catalyzed pericyclic reactions. In this report, we present an efficient and straightforward methodology to access bicyclic carbo- and heterocyclic scaffolds combining different ring sizes through transannular Morita-Baylis-Hillman reaction catalyzed by a chiral enantiopure bifunctional phosphine. The reaction is remarkably wide in scope and enables the use of a variety of medium and large size ketoenone substrates leading to the final products in high yields and providing excellent stereocontrol in the formation of a quaternary stereogenic center at the ring fusion. Moreover, its potential as a general tool in organic synthesis has been highlighted through the accomplishment of the first enantioselective total synthesis of (-)-γ-gurjunene, a sesquiterpene natural product.

15.
Blood ; 129(4): 525-532, 2017 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-27811020

RESUMO

We evaluated the impact of recipient and cord blood unit (CBU) genetic polymorphisms related to immune response on outcomes after unrelated cord blood transplantations (CBTs). Pretransplant DNA samples from 696 CBUs with malignant diseases were genotyped for NLRP1, NLRP2, NLRP3, TIRAP/Mal, IL10, REL, TNFRSF1B, and CTLA4. HLA compatibility was 6 of 6 in 10%, 5 of 6 in 39%, and ≥4 of 6 in 51% of transplants. Myeloablative conditioning was used in 80%, and in vivo T-cell depletion in 81%, of cases. The median number of total nucleated cells infused was 3.4 × 107/kg. In multivariable analysis, patients receiving CBUs with GG-CTLA4 genotype had poorer neutrophil recovery (hazard ratio [HR], 1.33; P = .02), increased nonrelapse mortality (NRM) (HR, 1.50; P < .01), and inferior disease-free survival (HR, 1.41; P = .02). We performed the same analysis in a more homogeneous subset of cohort 1 (cohort 2, n = 305) of patients who received transplants for acute leukemia, all given a myeloablative conditioning regimen, and with available allele HLA typing (HLA-A, -B, -C, and -DRB1). In this more homogeneous but smaller cohort, we were able to demonstrate that GG-CTLA4-CBU was associated with increased NRM (HR, 1.85; P = .01). Use of GG-CTLA4-CBU was associated with higher mortality after CBT, which may be a useful criterion for CBU selection, when multiple CBUs are available.


Assuntos
Antígeno CTLA-4/imunologia , Transplante de Células-Tronco de Sangue do Cordão Umbilical , Antígenos HLA/imunologia , Neoplasias Hematológicas/genética , Polimorfismo Genético , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Adolescente , Adulto , Alelos , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/imunologia , Antígeno CTLA-4/genética , Criança , Pré-Escolar , Intervalo Livre de Doença , Feminino , Sangue Fetal/citologia , Sangue Fetal/imunologia , Sangue Fetal/transplante , Expressão Gênica , Genótipo , Antígenos HLA/genética , Neoplasias Hematológicas/imunologia , Neoplasias Hematológicas/patologia , Neoplasias Hematológicas/terapia , Teste de Histocompatibilidade , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Agonistas Mieloablativos/uso terapêutico , Proteínas NLR , Modelos de Riscos Proporcionais , Isoformas de Proteínas/genética , Isoformas de Proteínas/imunologia , Estudos Retrospectivos , Condicionamento Pré-Transplante , Doadores não Relacionados
16.
Chemistry ; 24(35): 8764-8768, 2018 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-29645302

RESUMO

In this work, carboxylic acids, which are typically regarded as poor nucleophiles, are demonstrated to be competent reagents to promote the ring-opening of formylcyclopropanes after activation of the latter through iminium ion formation. Under optimized reaction conditions, a variety of γ-acyloxy-substituted aldehydes can be obtained in high yields and enantioselectivities through the desymmetrization of substituted meso-formylcyclopropanes in the presence of a chiral secondary amine as catalyst.

17.
Chemistry ; 24(53): 14059-14063, 2018 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-29901236

RESUMO

Complete stereocontrol on the transition-metal-free hydroboration of the distal double bond of allenamides could be achieved when allenamides contained acetyl substituents, which provided exclusively the Z-isomer. The consecutive Pd-catalyzed cross-coupling reaction allowed the straightforward formation of trisubstituted enamides, with total control of the stereoselectivity.

18.
Chemistry ; 24(61): 16262-16265, 2018 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-30175420

RESUMO

Highly enantioenriched, chromatographically-stable secondary allyl boronates featuring a 1,1,2,2-tetraethyl-1,2-ethanediol fragment (Epin) were obtained by kinetic resolution of their racemic mixtures. The Epin group at boron considerably improved stability of allyl boronates allowing them to be readily isolated by chromatography on silica. The resolved reagents were applied in stereoselective synthesis of homoallylic amines with an internal double bond employing unprotected imines formed in situ from aldehydes and ammonia. The reactions proceeded with an excellent transfer of chirality.

19.
J Org Chem ; 83(7): 4180-4189, 2018 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-29529372

RESUMO

A diastereodivergent approach to highly substituted bicyclo[3.1.0]hexanes has been developed through a transannular alkylation reaction that builds up the bicyclic core employing asymmetric organocatalysis as the tool for the installation of all stereocenters. On one hand, a Michael/Michael cascade process between enals and 4-alkenyl sulfamidate imines under the iminium/enamine activation manifold provides an oxathiazole-2,2-dioxide-fused cyclohexane adduct that, after isolation, is subsequently engaged in a transannular alkylation/hydrolysis through enamine activation by the use of a primary amine. On the other hand, the corresponding C-2 epimers are directly obtained from the same starting materials in a single operation through a cascade Michael/Michael/transannular alkylation/hydrolysis sequence through sequential iminium/enamine/enamine combination of aminocatalytic activation manifolds.

20.
Angew Chem Int Ed Engl ; 57(27): 8225-8229, 2018 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-29741812

RESUMO

Racemic cyclopropyl ketones undergo enantioselective rearrangement to deliver the corresponding dihydrofurans in the presence of a chiral phosphoric acid as the catalyst. The reaction involves activation of the donor-acceptor cyclopropane substrate by the chiral Brønsted acid catalyst to promote the ring-opening event, thus generating a carbocationic intermediate that subsequently undergoes cyclization. Computational studies and control experiments support this mechanistic pathway.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA