RESUMO
Systematic investigations on the reactions between cis-[M(dppm)2 Cl2 ] (M=Ru/Os; dppm=1,1-bis(diphenylphosphino)methane) and pyridine/quinoline substituted homopropargylic alcohols uncovered the diverse Ru(II)/Os(II)-induced alkyne activation pathways. The alkynes underwent cyclization on M via a "non-vinylidene" pathway at lower temperatures, resulting in alkenyl intermediates which might further metallacyclize to give metallapyrroloindolizines. Conversely, reactions at higher temperatures induced alkyne cyclization on M via a "vinylidene" pathway, affording cyclic oxacarbene complexes. Additionally, a rare decyclization mechanism was observed during the transformation of a metallacyclization-resistant alkenyl complex into a cyclic oxacarbene complex. DFT calculations were employed to validate the experimental findings. Overall, these results not only provide insights into controlling alkyne activation pathways, but also offer new strategies for preparing metalated heterocyclic and metallacyclic complexes.
RESUMO
Mononuclear and dinuclear Ru(II) complexes cis-[Ru(κ2-dppm)(bpy)Cl2] (1), cis-[Ru(κ2-dppe)(bpy)Cl2] (2) and [Ru2(bpy)2(µ-dpam)2(µ-Cl)2](Cl)2 ([3](Cl)2) were prepared from the reactions between cis(Cl), cis(S)-[Ru(bpy)(dmso-S)2Cl2] and diphosphine/diarsine ligands (bpy = 2,2'-bipyridine; dppm = 1,1-bis(diphenylphosphino)methane; dppe = 1,2-bis(diphenylphosphino)ethane; dpam = 1,1-bis(diphenylarsino)methane). While methoxy-substituted ruthenafuran [Ru(bpy)(κ2-dppe)(C^O)]+ ([7]+; C^O = anionic bidentate [C(OMe)CHC(Ph)O]- chelate) was obtained as the only product in the reaction between 2 and phenyl ynone HC≡C(C=O)Ph in MeOH, replacing 2 with 1 led to the formation of both methoxy-substituted ruthenafuran [Ru(bpy)(κ2-dppm)(C^O)]+ ([4]+) and phosphonium-ring-fused bicyclic ruthenafuran [Ru(bpy)(P^C^O)Cl]+ ([5]+; P^C^O = neutral tridentate [(Ph)2PCH2P(Ph)2CCHC(Ph)O] chelate). All of these aforementioned metallafuran complexes were derived from Ru(II)-vinylidene intermediates. The potential applications of these metallafuran complexes as anticancer agents were evaluated by in vitro cytotoxicity studies against cervical carcinoma (HeLa) cancer cell line. All the ruthenafuran complexes were found to be one order of magnitude more cytotoxic than cisplatin, which is one of the metal-based anticancer agents being widely used currently.
Assuntos
Fosfinas , Rutênio , Ligantes , Metano , Fosfinas/farmacologia , Rutênio/químicaRESUMO
Metallafuran complexes with a fused five-membered phosphonium ring were synthesized from reactions between terminal ynones HC≡C(C=O)R and cis-[Ru/Os(dppm)2 Cl2 ] (dppm=1,1-bis(diphenylphosphino)methane). A metal-vinylidene-involving pathway was found to be an energetically feasible formation mechanism for these complexes. These phosphonium-containing metallafurans, like many phosphonium-functionalized drugs, have the ability to induce mitochondrial dysfunction. They also exhibit stronger cytotoxicity against several human cancer cell lines in comparison with their metal precursors and the classic anticancer drug cisplatin. Overall, this work provides structural and mechanistic insights for the rational design of functional metallacycles via activation of alkynes by RuII and OsII centers.
RESUMO
The first C3-metalated indolizine complex was prepared from the reaction between cis-[Os(dppm)2Cl2] (dppm = 1,1-bis(diphenylphosphino)methane) and propargylic pyridine, HC[triple bond, length as m-dash]CC(OH)(2-py)2. A phosphonium ring-fused bicyclic osmafuran complex was also prepared from the reaction between cis-[Os(dppm)2Cl2] and pyridyl ynone, HC[triple bond, length as m-dash]C(C[double bond, length as m-dash]O)(2-py). The formation of these two products revealed the intermediacy of metal-vinylidene species regarding [Os(dppm)2Cl]+-mediated alkyne transformations. Comparison of the d6 transition-metal precursors employed to activate HC[triple bond, length as m-dash]CC(OH)(2-py)2 suggests that precursors with higher π-basicity favor the vinylidene-involving pathway.
RESUMO
The two families of RuII -chromene and -chromone complexes isolated in this work represent the first examples of metalated chromene and chromone complexes synthesized through transition-metal-mediated cyclization of phenol-tethered ynone. These unprecedented metalated heterocyclic compounds exhibit remarkable features, such as pH-switchable metal-carbon bonding interactions, photo-triggerable release of organic chromone upon visible-light irradiation, and superior antioxidative property to their organic analogue (1,4-benzopyrone). These findings not only offer mechanistic insights into metal-induced activation of functionalized alkynes, but also add a new dimension to rational design of antioxidants and photo-responsive drug delivery systems.
Assuntos
Antioxidantes/química , Carbono/química , Cromonas/química , Complexos de Coordenação/química , Metais/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/toxicidade , Portadores de Fármacos/química , Humanos , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Conformação Molecular , Rutênio/química , EspectrofotometriaRESUMO
Two types of unexpected quinolizinium complexes were obtained from the reactions between pyridine-functionalized propargylic alcohol HC[triple bond, length as m-dash]CC(OH)(Ph)(CH2(2-py)) (L1) and cis-[M(L^L)2Cl2] (M = Ru, Os; L^L = 1,1-bis(diphenylphosphino)methane (dppm), 2,2'-bipyridine (bpy)). Their molecular structures revealed that L1 can be activated by Ru and Os via the conventional "vinylidene-involving" or unconventional "non-vinylidene-involving" pathways.
RESUMO
Reactions between pyridine-functionalized alkynes and an Fe(ii) precursor supported by 2,5,8-trithia[9](2,9)-1,10-phenanthrolinophane afforded the first Fe(ii)-indolizine and -indolizinone complexes. Structural analysis and theoretical calculations revealed the existence of unconventional "non-vinylidene" pathways and challenged the generality of vinylidene intermediacy in Fe(ii)-induced alkyne transformations.
RESUMO
The two series of ruthenium-indolizinone complexes prepared by Ru-mediated cyclization of pyridine-tethered alkynes represent the first examples of metalated indolizinone complexes. Joint experimental-theoretical investigation suggests an unconventional 5-endo-dig cyclization pathway as their formation mechanism. They also exhibit moderate cytotoxicity against several human cancer cell lines.