N‐Heterocyclic and Mesoionic Carbenes of Manganese and Rhenium in Catalysis

Friães, Sofia; Realista, Sara; Mourão, Henrique; Royo, Beatriz

doi:10.1002/ejic.202100884

Cited by 19 publications

(21 citation statements)

References 73 publications

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“…Over the last few decades, metal complexes bearing N-heterocyclic carbene (NHC) ligands have proved to be a worthy substitute for expensive phosphine-based complexes for catalyzing several C–C, C–N, and C–O coupling and hydrogen transfer reactions . Earlier, chelating bis-NHC complexes of 4d and 5d transition metals have shown significant catalytic activity toward several hydrogen transfer reactions. − , With the advancement in 3d-metal catalysis, bis-NHC-Mn(I) complexes have recently been proven immensely useful for catalyzing various alcohol dehydrogenative coupling reactions . Seminal works by the Ke group who reported a methyl wingtip containing chelating bis-NHC-Mn(I) complex for the N-alkylation of anilines with alcohols and the synthesis of α-alkylated ketones and quinolines following the alcohol dehydrogenative coupling strategy are noteworthy. , In 2020, they reported a bis-carbene-(CNC)Mn(I) complex for the acceptor-less dehydrogenative coupling between primary and secondary alcohols to the corresponding ketones .…”

Section: Introductionmentioning

confidence: 99%

Well-Defined Bis(NHC)Mn(I) Complex Catalyzed Tandem Transformation of α,β-Unsaturated Ketones to α-Methylated Ketones Using Methanol

2022

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Tandem transformation of α,β-unsaturated ketones to α-methylated ketones by utilizing methanol as both the hydrogen and C1 sources is reported in the presence of a phosphine-free bis-N-heterocyclic carbene-Mn(I) (bis-NHC-Mn(I)) catalyst. The dehydrogenative coupling between methanol and α,β-unsaturated ketones produces the corresponding α-methylated ketones along with 1 equiv of formaldehyde and water. Among different bis-NHC-Mn(I) complexes, the ethyl wingtip-substituted complex with a triflate counteranion showed the highest catalytic activity. This catalytic system was highly effective for the reductive methylation of a wide variety of substrates including aromatic, heteroaromatic, and aliphatic straight chains containing α,β-unsaturated ketones. Notably, this methodology led to the synthesis of pharmaceutically important drug molecules such as eperisone and lanperisone. Several control experiments, kinetic studies, Hammett studies, and density functional theory (DFT) calculations were carried out to understand this tandem catalytic process.

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Section: Introductionmentioning

confidence: 99%

Well-Defined Bis(NHC)Mn(I) Complex Catalyzed Tandem Transformation of α,β-Unsaturated Ketones to α-Methylated Ketones Using Methanol

2022

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“…38 Despite these interesting features, the chemistry and catalysis of Mn with MICs have remained elusive. 35,36 In this work, we report the synthesis and characterization of a new family of tricarbonyl Mn(I) complexes bearing bis(1,2,3triazol-5-ylidene) ligands and their catalytic performance in the N-alkylation of anilines with alcohols. In addition, related Re(I) triazolylidene complexes have been prepared and applied in this catalytic process to compare the activity of Mn and Re complexes.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Later, other authors showed the capability of this complex to efficiently catalyze the N-alkylation of anilines with alcohols, the α-alkylation of ketones with alcohols, and, more recently, the transformation of α,β-unsaturated ketones to α-methylated ketones using methanol . Apart from classical imidazolium-derived NHCs, we are also interested in the chemistry of manganese with mesoionic carbenes (MICs). − MICs, especially those derived from 1,2,3-triazolylidenes, make up an interesting subclass of NHCs that have advanced to become a prominent class of ligands in catalysis. − In many cases, their strong σ-donor and weak π-acceptor properties yield metal complexes with enhanced catalytic activities and stability . Despite these interesting features, the chemistry and catalysis of Mn with MICs have remained elusive. , …”

Section: Introductionmentioning

confidence: 99%

Bis-Triazolylidenes of Manganese and Rhenium and Their Catalytic Application in N-Alkylation of Amines with Alcohols

2023

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A new family of air-stable Mn and Re complexes bearing bidentate bis(1,2,3-triazol-5-ylidene) ligands with the general formula [M(bis-triazolylidene)(CO)3X] (M = Mn or Re; X = Cl or Br), containing a methylene linker or a direct link between the two triazolylidene ligands, is presented. All complexes have been applied as catalysts for the N-alkylation of anilines with benzylic alcohols. The Mn complex bearing a bis-triazolylidene with a methylene bridge between the two triazolylidene fragments was shown to be a highly efficient catalyst, affording the corresponding amine in 92% yield in the presence of a low base loading (t-BuOK, 0.1 equiv). Comparison between Mn complexes bearing imidazolium- and triazolium-derived N-heterocyclic carbene ligands showed that Mn triazolylidenes displayed higher catalytic activity when a low base loading was used.

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“…Over the last two decades, NHC-transition metal complexes (NHC = N-Heterocyclic Carbene) have attracted significant attention not only for uses in organometallic chemistry and catalysis − but also as bio-organometallics, notably due to the high stability of the NHC-metal bonds under physiological conditions. − …”

Section: Introductionmentioning

confidence: 99%

Anti-Cancer and Radio-Sensitizing Properties of New Bimetallic (N-Heterocyclic Carbene)-Amine-Pt(II) Complexes

Jia,

Diane,

Ghosh

et al. 2023

J. Med. Chem.

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Bioactive NHC-transition metal complexes have shown promise as anti-cancer agents, but their potential use as radiosensitizers has been neglected so far. We disclose here a new series of bimetallic platinum(II) complexes displaying NHC-type bridging ligands, (bis-NHC)[trans-Pt(RNH2)I2]2, that have been synthesized via a simple, two-step procedure. They display cytotoxicity in the micromolar range on cancerous cell lines, accumulate in cells, and bind to genomic DNA, by inducing DNA damages. Notably, these bimetallic complexes demonstrate significant radiosensitizing effects on both ovarian cells A2780 and nonsmall lung carcinoma cells H1299. Further investigations revealed that bimetallic species make irradiation-induced DNA damages more persistent by inhibiting repair mechanisms. Indeed, a higher and persistent accumulation of both γ-H2AX and 53BP1 foci post-irradiation was detected, in the presence of the NHC-Pt complexes. Overall, we provide the first in vitro evidence for the radiosensitizing properties of NHC-platinum complexes, which suggests their potential use in combined chemo-radio therapy protocols.

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N‐Heterocyclic and Mesoionic Carbenes of Manganese and Rhenium in Catalysis

Cited by 19 publications

References 73 publications

Well-Defined Bis(NHC)Mn(I) Complex Catalyzed Tandem Transformation of α,β-Unsaturated Ketones to α-Methylated Ketones Using Methanol

Well-Defined Bis(NHC)Mn(I) Complex Catalyzed Tandem Transformation of α,β-Unsaturated Ketones to α-Methylated Ketones Using Methanol

Bis-Triazolylidenes of Manganese and Rhenium and Their Catalytic Application in N-Alkylation of Amines with Alcohols

Anti-Cancer and Radio-Sensitizing Properties of New Bimetallic (N-Heterocyclic Carbene)-Amine-Pt(II) Complexes

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