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1.
J Am Chem Soc ; 146(8): 5643-5649, 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38327018

RESUMO

We developed a method for the enantioselective synthesis of germanium-stereogenic compounds by the desymmetric carbene insertion of dihydrogermanes. A chiral rhodium phosphate catalyst decomposes diaryldiazo-methanes to generate rhodium carbenes that insert enantioselectively into one of the two Ge-H bonds of dihydrogermanes to form germanium-stereogenic compounds under mild reaction conditions. By this method, a variety of chiral germanes with germanium-stereogenic centers were synthesized in high yields and excellent enantioselectivities. Kinetic studies of the reaction showed that the diazo decomposition process was the rate-determining step. The remaining Ge-H bond of the chiral germane products provides a possibility for preparing chiral tetra-substituted germanium-stereogenic compounds.

2.
J Am Chem Soc ; 146(5): 3458-3470, 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38270100

RESUMO

Ligand modulation of transition-metal catalysts to achieve optimal reactivity and selectivity in alkene hydrofunctionalization is a fundamental challenge in synthetic organic chemistry. Hydroaminoalkylation, an atom-economical approach for alkylating amines using alkenes, is particularly significant for amine synthesis in the pharmaceutical, agrochemical, and fine chemical industries. However, the existing methods usually require specific substrate combinations to achieve precise regio- and stereoselectivity, which limits their practical utility. Protocols allowing for regiodivergent hydroaminoalkylation from the same starting materials, controlling both regiochemical and stereochemical outcomes, are currently absent. Herein, we report a ligand-controlled, regiodivergent nickel-catalyzed hydroaminoalkylation of unactivated alkenes with N-sulfonyl amines. The reaction initiates with amine dehydrogenation and involves aza-nickelacycle intermediates. Tritert-butylphosphine promotes branched regioselectivity and syn diastereoselectivity, whereas ethyldiphenylphosphine enables linear selectivity, yielding regioisomers with inverse orientation. Systematic evaluation of diverse monodentate phosphine ligands reveals distinct regioselectivity cliffs, and % Vbur (min), a ligand steric descriptor, was established as a predictive parameter correlating ligand structure to regioselectivity. Computational investigations supported experimental findings, offering mechanistic insights into the origins of regioselectivity. Our method provides an efficient and predictable route for amine synthesis, demonstrating broad substrate scope, excellent tolerance toward various functional groups, and practical advantages. These include the use of readily available starting materials and cost-effective nickel(II) salts as precatalysts.

3.
J Am Chem Soc ; 146(22): 14915-14921, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38781401

RESUMO

Unactivated aliphatic alkenes are particularly desirable as starting materials because they are readily accessible in large quantities, but the enantioselective intermolecular reductive coupling of unactivated alkenes with imines is challenging. In this paper, we report a method for nickel-catalyzed intermolecular reductive coupling reactions between aliphatic alkenes and imines to yield chiral amines with excellent enantioselectivities and good linear selectivities. The reaction conditions are compatible with a broad range of aliphatic alkenes, including those derived from bioactive molecules. The success of this method can be attributed to the use of newly developed monodentate chiral spiro phosphine ligands.

4.
J Am Chem Soc ; 145(35): 19195-19201, 2023 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-37616490

RESUMO

We present the first enantioselective nickel-catalyzed borylative coupling of 1,3-dienes with aldehydes, providing an efficient route to highly valuable homoallylic alcohols in a single step. The reaction involves the 1,4-carboboration of dienes, leading to the formation of C-C and C-B bonds accompanied by the construction of two continuous stereogenic centers. Enabled by a chiral spiro phosphine-oxazoline nickel complex, this transformation yields products with exceptional diastereoselectivity, E-selectivity, and enantioselectivity. The diastereoselectivity of the reaction can be controlled by employing either (Z)-1,3-dienes or (E)-1,3-dienes.

5.
Angew Chem Int Ed Engl ; 62(24): e202304427, 2023 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-37057709

RESUMO

Chiral benzylic amines are privileged motifs in pharmacologically active molecules. Intramolecular enantioselective radical C(sp3 )-H functionalization by hydrogen-atom transfer has emerged as a straightforward, powerful tool for the synthesis of chiral amines, but methods for intermolecular enantioselective C(sp3 )-H amination remain elusive. Herein, we report a cationic copper catalytic system for intermolecular enantioselective benzylic C(sp3 )-H amination with peroxide as an oxidant. This mild, straightforward method can be used to transform an array of feedstock alkylarenes and amides into chiral amines with high enantioselectivities, and it has good functional group tolerance and broad substrate scope. More importantly, it can be used to synthesize bioactive molecules, including chiral drugs. Preliminary mechanistic studies indicate that the amination reaction involves benzylic radicals generated by hydrogen-atom transfer.

6.
J Obstet Gynaecol ; 42(7): 3149-3157, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35929918

RESUMO

Although ovarian cancer usually responds well to platinum- and taxane-based first-line chemotherapy, most patients develop recurrence and chemoresistance. Regenerating gene 4 (REG4) is a secretory protein involved in cell differentiation and proliferation. We found higher REG4 expression in ovarian cancer than in normal tissues (p < .05). Regenerating gene 4 expression was negatively associated with overall, progression-free or post-progression survival rates of patients with ovarian cancer receiving platinum or paclitaxel treatment (p < .05) according to a Kaplan-Meier plotter. Regenerating gene 4 overexpression resulted in either cisplatin or paclitaxel resistance, and apoptosis resistance in CAOV3 ovarian cancer cells (p < .05). REG4-transfected ovarian cancer cells showed stronger migration and invasion treated with cisplatin or paclitaxel (p < .05). Additionally, cisplatin or paclitaxel exposure led to the overexpression of phosphorylated phosphoinositide 3-kinase (p-PI3K), p-Akt, phosphorylated mammalian target of rapamycin (p-mTOR), glutathione S-transferase-π, survivin, and B-cell lymphoma 2 in REG4 transfectants compared with control cells (p < .05). These findings suggested that REG4 expression was up-regulated in ovarian cancer, and associated with poor survival and chemotherapy resistance. REG4 promoted the occurrence, development, and chemotherapy resistance of ovarian cancer by regulating cell proliferation, apoptosis, migration, and invasion, and PI3K/Akt/m-TOR signalling pathways. IMPACT STATEMENTWhat is already known on this subject? REG4 mRNA expression is up-regulated in many digestive cancers. High REG4 expression was associated with an adverse prognosis, high tumour and nodal stages, poor differentiation, and hepatic and peritoneal metastases of digestive cancers. REG4 expression conferred cancer cells with increased resistance to chemoradiotherapy, especially 5-FU-based treatment, by activating the MAPK/Erk/Bim signalling pathway.What do the results of this study add? REG4 was highly expressed in ovarian cancer. The expression of p-PI3K, p-AKT, p-mTOR, GST-π, survivin, and Bcl-2 was increased in REG4-overexpressing cells. High REG4 expression was significantly associated with inferior OS, PFS, and PPS rates in patients with ovarian cancer receiving platinum chemotherapy. REG4 mediated cisplatin and paclitaxel resistance in CAOV3 ovarian cancer cells. The percentage of apoptotic cells was markedly lower in REG4-transfected compared to mock-transfected cells after cisplatin or paclitaxel treatment.What are the implications of these findings for clinical practice and/or further research? This study aimed to evaluate the prognostic significance of REG4 expression in ovarian cancer treated with platinum and paclitaxel, to explore REG4 chemoresistance mechanisms to platinum and paclitaxel, and to provide a scientific experimental basis for the clinical treatment and outcome evaluation of ovarian cancer. In order to provide comprehensive clinical treatment of ovarian cancer, it is helpful to improve our understanding of multi-drug resistance and identify new cancer diagnostic biomarkers.


Assuntos
Cisplatino , Neoplasias Ovarianas , Proteínas Associadas a Pancreatite , Feminino , Humanos , Apoptose , Linhagem Celular Tumoral , Cisplatino/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Paclitaxel , Proteínas Associadas a Pancreatite/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Platina/farmacologia , Platina/uso terapêutico , Proteínas Proto-Oncogênicas c-akt/metabolismo , Survivina/metabolismo , Serina-Treonina Quinases TOR/metabolismo
7.
Angew Chem Int Ed Engl ; 61(11): e202115702, 2022 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-35043525

RESUMO

We have developed a nickel-catalyzed desymmetric reductive cyclization/coupling of 1,6-dienes. The reaction provides an efficient method for constructing a chiral tertiary alcohol and a quaternary stereocenter by a single operation. The method has excellent diastereoselectivity and high enantioselectivity, a broad substrate scope, as well as good tolerance of functional groups. Preliminary mechanism studies show that alkyl nickel(I) species are involved in the reaction.

8.
Angew Chem Int Ed Engl ; 61(18): e202117233, 2022 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-35112447

RESUMO

We report the first example of selective PdII -catalyzed tertiary C-H activation of cyclobutylmethyl ketones using a transient directing group. An electron-deficient 2-pyridone ligand was identified as the optimal external ligand to enable tertiary C-H activation. A variety of cyclobutylmethyl ketones bearing quaternary carbon centers was readily accessed without preinstalling internal directing groups in up to 81 % yield and >95 : 5 regioisomeric ratios of tertiary C-H arylation to ß-methylene (ß-methyl) or γ-C-H arylation.


Assuntos
Cetonas , Paládio , Carbono/química , Catálise , Cetonas/química , Ligantes , Paládio/química
9.
Angew Chem Int Ed Engl ; 60(6): 2948-2951, 2021 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-33094547

RESUMO

A highly enantio- and regioselective hydrosulfonylation of 1,3-dienes with sulfonyl hydrazides has been realized by using a palladium catalyst containing a monodentate chiral spiro phosphoramidite ligand. The reaction provided an efficient approach to synthetically useful chiral allylic sulfones. Mechanistic studies suggest that the reaction proceeds through the formation of an allyl hydrazine intermediate and subsequent rearrangement to the chiral allylic sulfone product. The transformation of the allyl hydrazine intermediate to the product is the enantioselectivity-determining step.

10.
Angew Chem Int Ed Engl ; 59(24): 9594-9600, 2020 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-32155313

RESUMO

The use of chiral transient directing groups (TDGs) is a promising approach for developing PdII -catalyzed enantioselective C(sp3 )-H activation reactions. However, this strategy is challenging because the stereogenic center on the TDG is often far from the C-H bond, and both TDG covalently attached to the substrate and free TDG are capable of coordinating to PdII centers, which can result in a mixture of reactive complexes. We report a PdII -catalyzed enantioselective ß-C(sp3 )-H arylation reaction of aliphatic ketones using a chiral TDG. A chiral trisubstituted cyclobutane was efficiently synthesized from a mono-substituted cyclobutane through sequential C-H arylation reactions, thus demonstrating the utility of this method for accessing structurally complex products from simple starting materials. The use of an electron-deficient pyridone ligand is crucial for the observed enantioselectivity. Interestingly, employing different silver salts can reverse the enantioselectivity.


Assuntos
Ciclobutanos/química , Cetonas/química , Paládio/química , Benzeno/química , Catálise , Transporte de Elétrons , Estereoisomerismo
11.
J Am Chem Soc ; 141(7): 2889-2893, 2019 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-30735367

RESUMO

A functional group exchange reaction between allylamines and alkenes via nickel-catalyzed C-C bond cleavage and formation was developed. This reaction provides a novel protocol, which does not require the use of unstable imine substrates, for the synthesis of allylamines, which are widely used in the production of fine chemicals, pharmaceuticals, and agrochemicals.

12.
J Am Chem Soc ; 140(37): 11627-11630, 2018 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-30183283

RESUMO

We developed a highly regioselective addition of 1,3-dienes with simple ketones by nickel-hydride catalyst bearing DTBM-SegPhos ligand. A wide range of aromatic and aliphatic ketones directly coupled with 1,3-dienes, providing synthetically useful γ,δ-unsaturated ketones in high yield and regioselectivity. The asymmetric version of the reaction was also realized in high enantioselectivity by using novel chiral ligand DTBM-HO-BIPHEP. The utility of this hydroalkylation was demonstrated by facile product modification and enantioselective synthesis of ( R)-flobufen.

13.
Angew Chem Int Ed Engl ; 57(2): 461-464, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29159912

RESUMO

A Ni-catalyzed hydroarylation of styrenes and 1,3-dienes with organoboron compounds has been developed. The reaction offers a highly selective approach to diarylalkanes and allylarenes under redox-neutral conditions. In this hydroarylation reaction, a new strategy that uses the proton of methanol to generate the active catalyst species Ni-H was developed. The Ni-catalyzed hydroarylation, combined with a Ir-catalyzed C-H borylation, affords a very efficient and straightforward access to a retinoic acid receptor agonist.

14.
Angew Chem Int Ed Engl ; 57(13): 3396-3400, 2018 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-29399987

RESUMO

A nickel(0)-catalyzed hydroalkenylation of imines with styrene and its derivatives is described. A wide range of aromatic and aliphatic imines directly coupled with styrene and its derivatives, thus providing various synthetically useful allylic amines with up to 95 % yield. The reaction offers a new atom- and step-economical approach to allylic amines by using alkenes instead of alkenyl-metallic reagents. Experiments and DFT calculations showed that TsNH2 promotes the proton transfer from the coordinated olefin to the imine, accompanied by a new C-C bond formation.

15.
Adv Exp Med Biol ; 1010: 247-260, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29098676

RESUMO

Physical therapy has the evidence-based science knowledge to address a wide range of physical and psychological problems of addiction. Neuromodulation techniques are becoming more and more important in the treatment of addiction. Here, the efficacy of different neuromodulation techniques in addiction, such as transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), deep brain stimulation (DBS), is critically evaluated. Other physical therapy methods including Biofeedback, Physical Activity and Acupuncture are also presented.


Assuntos
Comportamento Aditivo/terapia , Encéfalo/fisiopatologia , Usuários de Drogas/psicologia , Modalidades de Fisioterapia , Transtornos Relacionados ao Uso de Substâncias/terapia , Terapia por Acupuntura , Comportamento Aditivo/diagnóstico , Comportamento Aditivo/fisiopatologia , Comportamento Aditivo/psicologia , Biorretroalimentação Psicológica , Terapia por Estimulação Elétrica , Terapia por Exercício , Humanos , Modalidades de Fisioterapia/efeitos adversos , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Transtornos Relacionados ao Uso de Substâncias/fisiopatologia , Transtornos Relacionados ao Uso de Substâncias/psicologia , Resultado do Tratamento
16.
Adv Exp Med Biol ; 1010: 261-280, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29098677

RESUMO

Traditional Chinese Medicine(TCM) has been utilized in China for more than 2,000 years, and it has been practiced in treatment of substance addiction and non-substance addictions. TCM have efficacy in the rehabilitation of abnormal physical problems induced by chronic drug use, including improving immune function, increasing working memory, and protecting against neurological disorders. Given that TCM is potentially effective in the prevention of relapse, it has been suggested that TCM may be the ideal choice in the future for the treatment of opiate addiction. This review examines the significance of effective Chinese herbs and prescriptions for Drug Addiction, Alcohol addiction and food addiction.


Assuntos
Comportamento Aditivo/terapia , Encéfalo/efeitos dos fármacos , Usuários de Drogas/psicologia , Medicamentos de Ervas Chinesas/uso terapêutico , Transtornos Relacionados ao Uso de Substâncias/terapia , Terapia por Acupuntura/efeitos adversos , Alcoolismo/fisiopatologia , Alcoolismo/psicologia , Alcoolismo/terapia , Comportamento Aditivo/diagnóstico , Comportamento Aditivo/fisiopatologia , Comportamento Aditivo/psicologia , Encéfalo/fisiopatologia , Medicamentos de Ervas Chinesas/efeitos adversos , Dependência de Alimentos/fisiopatologia , Dependência de Alimentos/psicologia , Dependência de Alimentos/terapia , Humanos , Recidiva , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Transtornos Relacionados ao Uso de Substâncias/fisiopatologia , Transtornos Relacionados ao Uso de Substâncias/psicologia , Resultado do Tratamento
17.
Adv Exp Med Biol ; 1010: 281-293, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29098678
18.
J Am Chem Soc ; 138(9): 2957-60, 2016 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-26855263

RESUMO

The first nickel-catalyzed intermolecular hydroacylation reaction of alkenes with simple aldehydes has been developed. This reaction offers a new approach to the selective preparation of branched ketones in high yields (up to 99%) and branched selectivities (up to 99:1). Experimental data provide evidence for reversible formation of acyl-nickel-alkyl intermediate, and DFT calculations show that the aldehyde C-H bond transfer to a coordinated alkene without oxidative addition is involved. The origin of the reactivity and regioselectivity of this reaction was also investigated computationally, which are consistent with experimental observations.

19.
Tumour Biol ; 35(3): 1955-64, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24132590

RESUMO

Beclin 1, an important autophagy-related protein in human cells, is involved in autophagy, differentiation, anti-apoptosis, and cancer suppression, which is increased during periods of cell stress and extinguished during cell cycle. Human ovarian tumors display allelic loss of Beclin 1 with high frequency. To clarify Beclin 1's role in ovarian carcinogenesis and subsequent progression, its expression was examined by immunostaining on tissue microarrays containing ovarian normal tissue, benign and borderline tumors, and carcinomas. Beclin 1 mRNA and protein expression was examined in ovarian normal tissue, benign and borderline tumors, carcinoma tissue, and cell lines by reverse transcription polymerase chain reaction or Western blot, respectively. The results demonstrated that the higher Beclin 1 mRNA was observed in ovarian benign tumor than normal ovary and ovarian carcinoma (P < 0.05) and negatively correlated with the differentiation of ovarian carcinoma (P < 0.05). Beclin 1 protein expression was stronger in ovarian carcinoma than that in normal ovary and inversely related to the differentiation of ovarian carcinoma (P < 0.05) by Western blot. Immunohistochemically, Beclin 1 expression was statistically higher in ovarian borderline tumor and carcinoma than normal ovary and benign tumor (P < 0.05) and inversely linked to differentiation, lower ki-67 expression, and higher cumulative or relapse-free survival rate of ovarian carcinoma (P < 0.05). Cox proportional hazard model indicated that age and International Federation of Gynecology and Obstetrics staging (P < 0.05), but not pathological classification differentiation degree or Beclin 1 expression, were independent prognostic factors for overall and relapse-free ovarian carcinomas (P > 0.05). It was suggested that the aberrant Beclin 1 expression is closely linked to tumorigenesis and differentiation of ovarian carcinoma. Beclin 1 expression might be employed to indicate the worse prognosis of ovarian carcinomas, albeit not an independent factor.


Assuntos
Proteínas Reguladoras de Apoptose/biossíntese , Biomarcadores Tumorais/análise , Diferenciação Celular , Proteínas de Membrana/biossíntese , Neoplasias Epiteliais e Glandulares/metabolismo , Neoplasias Ovarianas/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Proteínas Reguladoras de Apoptose/análise , Proteína Beclina-1 , Western Blotting , Carcinogênese , Carcinoma Epitelial do Ovário , Linhagem Celular Tumoral , Progressão da Doença , Intervalo Livre de Doença , Feminino , Humanos , Imuno-Histoquímica , Estimativa de Kaplan-Meier , Proteínas de Membrana/análise , Pessoa de Meia-Idade , Neoplasias Epiteliais e Glandulares/mortalidade , Neoplasias Epiteliais e Glandulares/patologia , Neoplasias Ovarianas/mortalidade , Neoplasias Ovarianas/patologia , Prognóstico , Modelos de Riscos Proporcionais , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise Serial de Tecidos , Adulto Jovem
20.
Histol Histopathol ; 39(1): 117-130, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37129345

RESUMO

Keratin 80 (KRT80) is a filament protein that participates in cell differentiation and the integrity of the epithelial barrier. Here, KRT80 expression was higher in gastric cancer compared with normal mucosa at both mRNA and protein levels by bioinformatic analysis, qRT-PCR and Western blot (p<0.05), however, the methylation of KRT80 was lower than in normal mucosa (p<0.05). There was a negative relationship between promoter methylation and expression level of KRT80 gene in gastric cancer (p<0.05). KRT80 mRNA and protein expression was positively correlated with the differentiation of gastric cancer (p<0.05), while KRT80 methylation was negatively associated with gastric cancer differentiation and p53 mutation (p<0.05). The expression of KRT80 mRNA was positively linked to the short survival time of gastric cancers (p<0.05). The differential genes of KRT80 mRNA were involved in ligand-receptor interaction, estrogen signal pathway, peptidase, filament and cytoskeleton, keratinocyte differentiation, vitamin D receptor, muscle contraction, and B cell-mediated immunity (p<0.05). KRT80-related genes were classified into cell adhesion and junction, cadherin binding, skin and epidermis development, and so forth (p<0.05). KRT80 knockdown suppressed proliferation, anti-apoptosis, anti-pyroptosis, migration, invasion and epithelial-mesenchymal transition in gastric cancer cells (p<0.05). These findings indicated that up-regulated expression of KRT80 played a crucial part in gastric carcinogenesis, and might be considered as a biological marker for aggressive behaviors and poor prognosis. Its silencing might be used as an approach of target therapy for gastric cancer patients.


Assuntos
Neoplasias Gástricas , Humanos , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Diferenciação Celular , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células , Transição Epitelial-Mesenquimal/genética , Regulação Neoplásica da Expressão Gênica , Prognóstico , RNA Mensageiro/metabolismo , Neoplasias Gástricas/metabolismo
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