RESUMO
In the presence of TiCl3, the reductive cyclization of tetrasubstituted enol esters bearing a 2-(ortho-nitroaryl) substituent affords 3-acyloxy-2,3-disubstituted indolenines in good yields. A domino process involving the partial reduction of nitro to a nitroso group followed by 5-center-6π-electrocyclization, 1,2-acyloxy migration, and the further reduction of the resulting nitrone intermediate accounts for the reaction outcome. The so-obtained indolenines are converted smoothly to 2,2-disubstituted oxindoles via a sequence of saponification and semipinacol rearrangement.
RESUMO
Significant inhibition of Aurora B was achieved by the synthesis of simplified fragments of benzosceptrins and oroidin belonging to the marine pyrrole-2-aminoimidazoles metabolites isolated from sponges. Evaluation of kinase inhibition enabled the discovery of a synthetically accessible rigid acetylenic structural analogue EL-228 (1), whose structure could be optimized into the potent CJ2-150 (37). Here we present the synthesis of new inhibitors of Aurora B kinase, which is an important target for cancer therapy through mitosis regulation. The biologically oriented synthesis yielded several nanomolar inhibitors. The optimized compound CJ2-150 (37) showed a non-ATP competitive allosteric mode of action in a mixed-type inhibition for Aurora B kinase. Molecular docking identified a probable binding mode in the allosteric site "F" and highlighted the key interactions with the protein. We describe the improvement of the inhibitory potency and specificity of the novel scaffold as well as the characterization of the mechanism of action.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Aurora Quinase B/antagonistas & inibidores , Poríferos/química , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Trifosfato de Adenosina/metabolismo , Regulação Alostérica , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Mitose/efeitos dos fármacos , Modelos Moleculares , Simulação de Acoplamento Molecular , Relação Estrutura-AtividadeRESUMO
The combined Lewis acid catalytic system, generated from molecular iodine and tritylium tetrafluoroborate effectively catalyzed the Friedel-Crafts (FC) arylation of diarylmethyl sulfides providing an efficient access to various unsymmetrical triarylmethanes. The addition of tritylium and iodine created a more active catalytic system to promote the cleavage of sulfidic C-S bonds.
RESUMO
Maximum-quantum (MaxQ) NMR experiments have been introduced to overcome issues related to peak overlap and high spectral density in the NMR spectra of aromatic mixtures. In MaxQ NMR, spin systems are separated on the basis of the highest-quantum coherence that they can form. MaxQ experiments are however time consuming and methods have been introduced to accelerate them. In this article, we demonstrate the ultrafast, single-scan acquisition of MaxQ NMR spectra using spatial encoding of the multiple-quantum dimension. So far, the spatial encoding methodology has been applied only for the encoding of up to double-quantum coherences, and here we show that it can be extended to higher coherence orders, to yield a massive reduction of the acquisition time of multi-quantum spectra of aromatic mixtures, and also to monitor chemical reactions.
RESUMO
The cleavage of sulfidic C-S bonds under visible-light irradiation was harnessed to generate carbocations under neutral conditions and synthesize valuable di- and triarylalkanes as well as benzyl amines. To this end, photoredox catalysis and direct photoinduced C-S bond cleavage are used as complementary approaches and participate in the versatility of the general strategy. Extensive mechanistic studies have demonstrated the diversity of the reaction mechanism at work in these different reactions.
RESUMO
Acidic hydrogen containing 2-isocyano-4-methylphenyl diphenylacetate, C22H17NO2, (I), was synthesized by the base-promoted reaction between 5-methylbenzoxazole and diphenylacetyl chloride. Achiral (I) crystallizes in the chiral P212121 space group. The C[triple-bond]N bond length is 1.164â (2)â Å and the angle between the OCO and 2-isocyano-4-methylphenyl planes is 69.10â (16)°. Molecules are linked via C=O...H(phenyl) and bifurcated N[triple-bond]C...H(phenyl)/N[triple-bond]C...H(methine) hydrogen bonds, forming one-dimensional arrays.
RESUMO
In the title compound, C16H11NO2·C5H9NO, the dihedral angles between the male-imide and phenyl rings are 34.7â (2) and 64.8â (2)°. In the crystal, the 2,3-di-phenyl-male-imide and 1-methyl-pyrrolidin-2-one mol-ecules form centrosymmetrical dimers via pairs of strong N-Hâ¯O hydrogen bonds and π-π stacking inter-actions between the two neighboring male-imide rings [centroid-centroid distance = 3.495â (2)â Å]. The dimers are further linked by weak C-Hâ¯O and C-Hâ¯π hydrogen bonds into a three-dimensional framework.