Rhodium-Catalyzed C═N Bond Formation through a Rebound Hydrolysis Mechanism and Application in β-Lactam Synthesis

Chen, Long; Zhang, Linxing; Shao, Ying; Xu, Guangyang; Zhang, Xinhao; Tang, Shengbiao; Sun, Jiangtao

doi:10.1021/acs.orglett.9b01312

Cited by 32 publications

(22 citation statements)

References 48 publications

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“…B3LYP-D3 functional has been widely applied in the theoretical studies on Rh-catalyzed reactions. ,− To further examine the reliability of our computations with B3LYP-D3(BJ), we compared the computed overall activation free energies and selectivities with three other popular density functionals, namely, PBE0-D3(BJ), ,, M06, and ωB97X-D, finding that different functionals exhibited consistent trends (see Supporting Information for details).…”

Section: Methodsmentioning

confidence: 99%

A Combined Computational and Experimental Study of Rh-Catalyzed C–H Silylation with Silacyclobutanes: Insights Leading to a More Efficient Catalyst System

Zhang

Wang

et al. 2021

J. Am. Chem. Soc.

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The study of new C−H silylation reagents and reactions remains an important topic. We reported that under Rh catalysis, silacyclobutanes (SCBs) for the first time were able to react with C(sp 2 )−H and C(sp 3 )−H bonds, however the underlying reasons for such a new reactivity were not understood. Through this combined computational and experimental study on C−H silylation with SCBs, we not only depict a reaction pathway that fully accounts for the reactivity and all the experimental findings but also streamline a more efficient catalyst that significantly improves the reaction rates and yields. Our key findings include: (1) the active catalytic species is a [Rh]−H as opposed to the previously proposed [Rh]−Cl; (2) the [Rh]−H is generated via a reductive elimination/β-hydride (β-H) elimination sequence, as opposed to previously proposed endocyclic β-H elimination; (3) the regio-and enantio-determining steps are identified; (4) and of the same importance, the discretely synthesized [Rh]−H is shown to be a more efficient catalyst. This work suggests that the [Rh]−H/diphosphine system should find further applications in C−H silylations involving SCBs.

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Section: Methodsmentioning

confidence: 99%

A Combined Computational and Experimental Study of Rh-Catalyzed C–H Silylation with Silacyclobutanes: Insights Leading to a More Efficient Catalyst System

Zhang

Wang

et al. 2021

J. Am. Chem. Soc.

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“…The preparation of Schiff bases can proceed by the condensation reaction of carbonyl compounds with primary amines. Apart from the condensation reaction commonly used in the synthesis of Schiff bases, other synthetic methods have been reported, such as the reductive imination of nitro compounds [3], rebound hydrolysis [4], hydroamination of alkynes with anilines [5], oxidative coupling of alcohols and amines [6] and cross-coupling of amines [7,8].…”

Section: Introductionmentioning

confidence: 99%

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

Adeleke

Zamisa

Omondi

2021

Molbank

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Imines are fundamental organic compounds used as synthetic intermediates and as ligands in coordination chemistry. They are also found to be important pharmacophores in various bioactive compounds. In this report, two Schiff bases were prepared using the traditional condensation of 4-pyridinecarboxaldehyde with 2-thiophenemethylamine and 2-quinolinecarboxaldehyde with furfurylamine to form (E)-1-(pyridin-4-yl)-N-(thiophen-2-ylmethyl)methanimine (L1) and (E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine (L2) respectively. L1 and L2 were complexed with silver perchlorate in 2:1 [M:L] stoichiometry to obtain complexes 1 and 2, respectively. The crystal structures of 1 and 2 were unequivocally determined by single-crystal X-ray diffraction analysis. The resulting structures revealed 2 to be a four-coordinate as expected. In contrast, an unexpected chemoselective hydrolytic cleavage of one mole of the (CH=N) imine ligands occurred in complex 2 and, further, the amines (thiophenemethylamine) homo-coupled to form a new imine ligand derivative in situ (L1a) before coordinating to the Ag(I) center along with L1. This observation described an alternative synthetic route to be explored to synthesize a diverse range of imine derivatives, which involves the Ag(I)-promoted homo-coupling of amines. Herein, the crystal structures of Ag(I) complexes of pyridinyl [Ag(L1)(L1a)]ClO4 (1) and quinolinyl [Ag(L2)2]ClO4 (2) Schiff bases are presented.

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“…The literature analysis revealed that the overwhelming majority of reported β-lactam syntheses that exploit the disconnection in question involve generating ketenes such as 7 via Rh(II) carbenes, which, in our view, somewhat tarnishes this approach compared to the convenience and practical simplicity of the catalyst-free Castagnoli–Cushman chemistry. Considering that there are also examples involving thermally and photochemically generated ketenes 7 in the literature, we set off to investigate the feasibility of thermally promoted cyclocondensation of α-acyl-α-diazoacetates 8 with imines as an entry into the β-lactam scaffold.…”

Section: Introductionmentioning

confidence: 99%

α-Acyl-α-diazoacetates in Transition-Metal-Free β-Lactam Synthesis

et al. 2019

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Thermally promoted reaction of α-acyl-α-diazoacetates with imines has been investigated. The transformation, earlier reported predominantly under transition metal catalyzed conditions, delivers α-alkoxycarbonyl-substituted β-lactams with outstanding diastereoselectivity. DFT calculations performed in order to evaluate energetically feasible reaction pathways revealed the intermediacy of 1,3-oxazin-4-one intermediates hitherto never implicated in the Staudinger synthesis of β-lactams.

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Rhodium-Catalyzed C═N Bond Formation through a Rebound Hydrolysis Mechanism and Application in β-Lactam Synthesis

Cited by 32 publications

References 48 publications

A Combined Computational and Experimental Study of Rh-Catalyzed C–H Silylation with Silacyclobutanes: Insights Leading to a More Efficient Catalyst System

A Combined Computational and Experimental Study of Rh-Catalyzed C–H Silylation with Silacyclobutanes: Insights Leading to a More Efficient Catalyst System

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

α-Acyl-α-diazoacetates in Transition-Metal-Free β-Lactam Synthesis

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