RESUMO
Starting with chiral vinyl sulfoxides and allenyl ketones or allenoates, a triflic acid-catalyzed asymmetric [3,3]-sigmatropic rearrangement of sulfoniums is reported to have a direct access to highly functionalized C4-chiral cyclopentenones (19 examples, up to 85% yield and >95% enantiomeric excesses). In addition to the use of these chiral compounds as key building blocks in organic synthesis, the antiproliferative activities of sulfoxide substrates and the corresponding cyclopentenones were evaluated, and promising cytotoxicity against the HL-60 human tumor cell line was found.
RESUMO
Dibenzotriazonine represent a new class of nine-membered cyclic azobenzenes with a nitrogen atom embedded in the bridging chain. To enable future applications of this photoactive backbone, we propose in this study the synthesis of mono- and dihalogenated triazonines, that allow the late-stage introduction of different functionalized aryl groups and heteroatoms (N, O, and P) via palladium-catalyzed reactions. Indeed, different diphenylphosphoryl-triazonines were synthesized with functional groups such as aniline or phenol. Bis(diphenylphosphoryl)phenyl mono- and bis-carbamate-triazonines were also isolated in good yields.
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We report herein the synthesis and characterization of a phosphorus-containing cyclic azobenzene as a new photoswitchable scaffold. This backbone reveals high bidirectional photoswitching yields and high thermal stability for both isomers, with t1/2 > 90 days at 60 °C. Both E- and Z-isomers have been characterized by UV-vis spectroscopy and X-ray crystallography.
RESUMO
An efficient and straightforward phosphine-promoted tandem aza-Michael addition/intramolecular Wittig reaction was developed for the synthesis of polyfunctionalized 2-azetines. After demonstrating that this transformation could be made catalytic in phosphine through in situ reduction of phosphine oxide with phenylsilane, different post-transformation steps have been demonstrated, including an original [2 + 2] photodimerization. Preliminary biological tests highlighted that these fluorinated 1,2-dihydroazete-2,3-dicarboxylates exhibited significant cytotoxicity against the human tumor cell line.
Assuntos
Azetinas , Fosfinas , Humanos , Ácidos Carboxílicos , Catálise , Benzoatos/químicaRESUMO
Cycloisomerization of N-tethered indole- and dihydropyrrole-arylpropargyl substrates into complex polycycles was investigated by using gold(I) catalysis. Enantioselectivities up to 93% ee were obtained in the asymmetric version of this process. DFT calculations rationalized the reactivity observed for the formation of such complex molecular frameworks.
RESUMO
A cationic gold(I)-catalyzed asymmetric [3,3]-sigmatropic rearrangement of sulfonium leads after cyclization to cyclopentenones with a C4-quaternary stereocenter. Starting with simple vinyl sulfoxides and propargyl silane, numerous compounds were isolated with moderate to good yields and excellent enantiomeric excesses (26 examples). The application of this simple methodology allowed the efficient total synthesis of five natural sesquiterpenoids, including enokipodin A and B, hitoyopodin A, lagopodin A, and isocuparene-3,4-diol.
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The Tethered Counterion-Directed Catalysis (TCDC) approach has been applied to the enantioselective Au(I) catalyzed dearomatizations of 1-naphthols with allenamides. Stereocontrol is ensured by the intramolecular ion-pairing between the chiral gold-tethered phosphate and an iminium unit, that provides a rigid, well-defined chiral environment to the key electrophilic intermediate.
RESUMO
We disclose here dibenzotriazonines as a new class of nine-membered cyclic azobenzenes displaying a nitrogen function in the saturated ring chain. The specific features of these compounds are (i) a preferred E-configuration, (ii) high bi-directional photoswitching and (iii) good thermal stability of both E- and Z-forms.
RESUMO
Diphosphines displaying azobenzene scaffolds and the corresponding bis-gold chloride complexes have been prepared and fully characterized by photophysical, spectroscopic and X-ray diffraction studies. DFT calculations provide complementary information on their electronic, structural and spectroscopic properties. Comparative investigations have been carried out on compounds featuring phosphorus functions in the meta- and para-positions, respectively, with respect to the azo functions, as well as on diphosphines with an ortho-tetrafluoro substituted azobenzene core. The effects of the substitution patterns on structural and spectroscopic properties are discussed.
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An efficient and straightforward gold-catalyzed protocol for the synthesis of 2-substituted 4-oxo-4-arylbutanal derivatives from commercially available or easily accessible alkynes and vinylsulfoxide substrates has been developed. Extension of the methodology to the use of 1-cycloalkenyl sulfoxides allowed the facile synthesis of five-, six-, and seven-membered-ring cycloalkyl-1-one backbone. Subsequently, the tetrahydrocycloalkyl[b]pyrrole derivatives, which are found in many active pharmaceutical ingredients, were isolated in good yields. Mechanistic investigation highlighted a [3,3]-sigmatropic rearrangement of a sulfonium intermediate in this process.
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An enantioselective Au(i)-catalyzed cyclization/nucleophilic addition process is developed, starting from 1,5-enyne substrates. A broad scope of O-, N- and C-nucleophiles was introduced in order to provide the corresponding chiral cyclopentene derivatives in moderate to high yields and up to 96 : 4 enantiomeric ratio.
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Tethering a metal complex to its phosphate counterion via a phosphine ligand enables a new strategy in asymmetric counteranion-directed catalysis (ACDC). A straightforward, scalable synthetic route gives access to the gold(I) complex of a phosphine displaying a chiral phosphoric acid function. The complex generates a catalytically active species with an unprecedented intramolecular relationship between the cationic Au(I) center and the phosphate counterion. The benefits of tethering the two functions of the catalyst are demonstrated here in a tandem cycloisomerization/nucleophilic addition reaction, by attaining high enantioselectivity levels (up to 97% ee) at an unusually low 0.2 mol % catalyst loading. Remarkably, the method is also compatible with a silver-free protocol.
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This study discloses the first enantioselective variant of the gold(I)-catalyzed hydrative cyclizations of ynamides, which have been implemented by using bis-gold(I) complexes of chiral diphosphines. Starting from N-propargyl-ynamides and water in the presence of p-toluenesulfonic acid, the cyclization reactions afford N-tosyl-3,6-dihydropyridin-2(1H)-ones in good isolated yields and with high levels of stereocontrol (20 examples, enantiomeric ratios up to 94:6).
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Phosphahelicenes with thiophosphinic acid and ester functions have been obtained by the oxidative photocyclisation of olefins bearing both a benzophenanthrene and a benzophosphole unit. When the method has been extended to olefins bearing a partially saturated benzophospholene unit, a divergent regioselectivity of the photocyclisation step has been observed, leading to new helicenes in which the phosphorus function is located on the external rim of the helical backbone. The observed regioselectivity correlates well with the free-valence numbers of the atoms involved in the photocyclisation reaction (DFT calculations).
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We herein demonstrated a N-hydroxyphthalimide (NHPI)-mediated chemo- and regioselective radical cyclization of yne-dienone with thiols to construct 3-thioaryl bearing [6,6]-fused dihydrochromenone derivatives. This transformation tolerates common functional groups and has broad scope. The reaction proceeds via the attack of a thioaryl radical to alkyne over the activated Michael acceptor. The TEMPO quenching experiment suggests the involvement of a radical intermediate. Synthetic versatility of 3-thioaryldihydrochromenones is also showcased.
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In the present study, we report the first enantioselective and highly efficient phosphine-catalyzed process via a chemoselective in situ phosphine oxide reduction. Starting with 4,4,4-trifluorobutane-1,3-dione and dialkyl acetylenedicarboxylate substrates, highly functionalized fluorinated cyclobutenes were obtained in excellent yields and enantioselectivities. Using the same methodology, CF3-spirocyclobutene derivatives were also synthesized (34 examples, up to 95% ee).
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As a complement to our previous studies on the development of a class of chiral phosphahelicenes, this article discloses the synthesis, spectroscopic, and structural characterizations of a new phosphahelicene transition metal complex. It demonstrates the ability of these hindered chiral ligands to coordinate Pd (II) in trans-complexes Cl2 Pd(L*)2 . In the solid state, the complex adopts a C2-symmetric arrangement with two ligands facing each other on the same face of the coordination plane. X-Ray data highlight bending of the Pd (II) unit from the expected planar coordination geometry that might be due to a significant π-π stacking effect between the central rings of two helical units.
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Herein, the experimental physicochemical and chiroptical properties of a series of phosphahelicenes are reported, focusing on their UV/Vis absorption, luminescence, electronic circular dichroism, optical rotations, and circularly polarized luminescence. Furthermore, detailed analysis of absorption and ECD spectra performed with the help of quantum-chemical calculations allowed us to highlight general features of these helicenic phosphines. Finally, due to well-suited electrochemical properties and thermal stability, the systems were successfully used as emitters in organic light-emitting diodes.
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3,3'-Spirocyclopentene oxindoles structurally related to Wang's spiropyrrolidine oxindoles have been highlighted as a new class of antiproliferative agents against cancer cell lines with wild-type p53 status (IC50 up to 0.96 µM on SJSA-1 and 2.9 µM in HCT116 p53-wt). Inhibition of the MDM2-p53 interactions has been demonstrated through in vitro HTRF assays (IC50 up to 3.1 nM), while Western blot analysis showed activation of p53 selectively in HCT116 cancer cell lines with wild-type p53.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Oxindóis/química , Oxindóis/farmacologia , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Compostos de Espiro/química , Proteína Supressora de Tumor p53/metabolismo , Proliferação de Células/efeitos dos fármacos , Desenho de Fármacos , Células HCT116 , Humanos , Modelos Moleculares , Conformação Molecular , Ligação Proteica/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
A series of 1,2-dihydroquinolines were synthesized in good to excellent yields by reacting 2-aminobenzaldehyde derivatives and dialkyl acetylenedicarboxylates with catalytic amounts of phosphine. This reaction was rendered catalytic by the selective in situ phosphine oxide reduction with the use of phenylsilane. Furthermore, with the same starting materials and with an additional role of the reducing agent, a new olefination reaction was discovered. Hydrogen/deuterium (H/D) exchange experiments revealed the possible mechanism of this reaction.