Hemilabile N-heterocyclic carbene (NHC)-nitrogen-phosphine mediated Ru (II)-catalyzed N-alkylation of aromatic amine with alcohol efficiently

Yu, Xiaojun; He, Hai-Yu; Yang, Lei; Fu, Haiyan; Zheng, Xueli; Chen, Hua; Li, Ruixiang

doi:10.1016/j.catcom.2017.03.007

Cited by 35 publications

(20 citation statements)

References 36 publications

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“…The phenomenon of ligand hemilability is often employed to rationalize reactivity of organometallic compounds 36 – 41 , especially in the context of hybrid and multidentate ligands 42 – 44 . Invoked mainly for labile donor groups, e.g., oxygen or nitrogen 43 , hemilability is scarce for phosphine donors in general 45 – 47 and for manganese phosphines in particular 48 , 49 . In case on MnCNP complexes, generation of hydride complex 6 presents an attractive activation protocol for 3 .…”

Section: Resultsmentioning

confidence: 99%

Robust and efficient hydrogenation of carbonyl compounds catalysed by mixed donor Mn(I) pincer complexes

et al. 2021

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Any catalyst should be efficient and stable to be implemented in practice. This requirement is particularly valid for manganese hydrogenation catalysts. While representing a more sustainable alternative to conventional noble metal-based systems, manganese hydrogenation catalysts are prone to degrade under catalytic conditions once operation temperatures are high. Herein, we report a highly efficient Mn(I)-CNP pre-catalyst which gives rise to the excellent productivity (TOF° up to 41 000 h−1) and stability (TON up to 200 000) in hydrogenation catalysis. This system enables near-quantitative hydrogenation of ketones, imines, aldehydes and formate esters at the catalyst loadings as low as 5–200 p.p.m. Our analysis points to the crucial role of the catalyst activation step for the catalytic performance and stability of the system. While conventional activation employing alkoxide bases can ultimately provide catalytically competent species under hydrogen atmosphere, activation of Mn(I) pre-catalyst with hydride donor promoters, e.g. KHBEt3, dramatically improves catalytic performance of the system and eliminates induction times associated with slow catalyst activation.

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Section: Resultsmentioning

confidence: 99%

Robust and efficient hydrogenation of carbonyl compounds catalysed by mixed donor Mn(I) pincer complexes

et al. 2021

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“…Initially, mixing of PdCl 2 (MeCN) 2 with the diphosphine ligand in CO atmosphere leads to the formation of an active Pd(0)-intermediate ( A ). In cycle I, when L4 as a more suitable precursor to a hemilabile P,C-hybrid ligand is applied, intermediate B will be readily formed, wherein the involved P,C-hybrid ligand is featured with hemilabile “coordination–dissociation” character. − Immediately, the intermediate B serving as the real active catalyst is oxidatively added by ArI to afford intermediate C , which is able to irreversibly dissociate the labile PPh 2 fragment to make accommodation for the amine to form intermediate D upon scavenging HI by K 2 CO 3 and concurrent CO-coordination. D is then rapidly converted to acylpalladium intermediate E after CO insertion to the Pd–Ar bond along with the second CO coordination.…”

Section: Resultsmentioning

confidence: 99%

“…First, due to the stronger σ-donating ability as well as the weaker π-accepting nature, carbene ligands can form a more stable MC bond with a bond energy higher than that of the typical M–P bond if phosphines are involved, which is beneficial to the stability of the transition-metal catalysts; Second, P,C-hybrid ligands possess one weakly coordinating group (soft P-donor) that can reversibly release during the catalytic cycle providing unsaturation at the metal center. Thus, the less strongly bound moiety (−PPh 2 ) of this ligand, called hemilabile, is capable of temporarily holding a coordination site on the metal for protection and then being released for the substrate insertion timely. − Obviously, the available carbene can protect the metal catalytic center against deactivation via the consolidated MC ligation, while the coexisting phosphino-moiety can dissociate in a timely manner from the metal center to accommodate substrate activation. Third, the coordination nature of the P,C-hybrid ligands is sensitively discriminated by their steric and electronic properties.…”

Section: Introductionmentioning

confidence: 82%

Pd-Catalyst Containing a Hemilabile P,C-Hybrid Ligand in Amino Dicarbonylation of Aryl Halides for Synthesis of α-Ketoamides

et al. 2021

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The amino dicarbonylation of aryl halides affording α-ketoamides with Pd catalysts is highly dependent on the stereoelectronic properties of the involved ligands. Ionic diphosphine ligand L4 can serve as precursor of a hemilabile P,C (phosphine, carbene)-hybrid ligand to form a stable Pd(II)complex, Pd-L4. In contrast, analogues L1−L3 with a similar 1-(thiophen-3-yl)-benzimidazolyl skeleton behave as typical (mono/ di)phosphines. The catalytic system resulting from the complexation of PdCl 2 (MeCN) 2 and L4 exhibits good catalytic performance in terms of aryl iodides conversion (81−95%) and αketoamide selectivity (80−91%), as well as the available recyclability in the RTIL of [Bpy]BF 4 . The in situ FT-IR analysis reveals that the PdCl 2 (MeCN) 2 −L4 catalytic system favors the amino dicarbonylation toward α-ketoamides according to the proposed mechanism of cycle I, which involves two independent COinsertion steps.

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“…In general, homogeneous catalysts of metal complexes (i.e., Ru, Ir, Rh, Pt, Au, Ni, Cu, and Fe) have been used in amine alkylation with alcohols [6,7,8,9,10]. Nonetheless, homogeneous catalysts present a complicated separation of the reaction medium, making it difficult to isolate them from the obtained products.…”

Section: Introductionmentioning

confidence: 99%

Fe-Containing MOFs as Seeds for the Preparation of Highly Active Fe/Al-SBA-15 Catalysts in the N-Alkylation of Aniline

et al. 2019

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We have successfully incorporated iron species into mesoporous aluminosilicates (AlSBA15) using a simple mechanochemical milling method. The catalysts were characterized by nitrogen physisorption, inductively coupled plasma mass spectrometry (ICP-MS), pyridine (PY) and 2,6-dimethylpyridine (DMPY) pulse chromatography titration, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The catalysts were tested in the N-alkylation reaction of aniline with benzyl alcohol for imine production. According to the results, the iron sources, acidity of catalyst and reaction conditions were important factors influencing the reaction. The catalyst showed excellent catalytic performance, achieving 97% of aniline conversion and 96% of imine selectivity under optimized conditions.

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Hemilabile N-heterocyclic carbene (NHC)-nitrogen-phosphine mediated Ru (II)-catalyzed N-alkylation of aromatic amine with alcohol efficiently

Cited by 35 publications

References 36 publications

Robust and efficient hydrogenation of carbonyl compounds catalysed by mixed donor Mn(I) pincer complexes

Robust and efficient hydrogenation of carbonyl compounds catalysed by mixed donor Mn(I) pincer complexes

Pd-Catalyst Containing a Hemilabile P,C-Hybrid Ligand in Amino Dicarbonylation of Aryl Halides for Synthesis of α-Ketoamides

Fe-Containing MOFs as Seeds for the Preparation of Highly Active Fe/Al-SBA-15 Catalysts in the N-Alkylation of Aniline

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