Recent progress towards the transition-metal-catalyzed Nazarov cyclization of alkynes <i>via</i> metal carbenes

Ru, Guang-Xin; Zhang, Tingting; Zhang, Meng; Jiang, Xiaoyu; Zheng-kai, Wan; Zhu, Xiu-Hong; Shen, Wen-Bo; Gao, Guangqin

doi:10.1039/d1ob00744k

Cited by 20 publications

(4 citation statements)

References 135 publications

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“…Alkynes, as emerging non-diazo carbene precursors, have been gaining much attention recently [ 32 , 33 ]. Increasing numbers of carbene transfer reactions are being reported, starting from functionalized alkynes under the catalysis of transition metals.…”

Section: Introductionmentioning

confidence: 99%

X-H Bond Insertion Promoted by Heterogeneous Dirhodium Metal–Organic Cage with Alkynes as Safe Carbene Precursors

Chen

Zhao

et al. 2023

Molecules

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A facile and efficient methodology for the generation of the C-X (X = Si, B) bond through a carbene insertion process was demonstrated using a dirhodium metal–organic cage, MOC-Rh-1, as a heterogeneous catalyst. A series of functionalized alkynes were utilized as safe carbene precursors to furnish Si-H and B-H insertion products in moderate to excellent yields. These reactions featured a high atom-economy, a broad substrate scope, and mild reaction conditions. Moreover, the as-prepared MOC-Rh-1 catalyst was recovered easily from the reaction system by simple centrifugation and reused for ten runs without a significant loss in activity, which made good use of the valuable precious metal rhodium.

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Section: Introductionmentioning

confidence: 99%

X-H Bond Insertion Promoted by Heterogeneous Dirhodium Metal–Organic Cage with Alkynes as Safe Carbene Precursors

Chen

Zhao

et al. 2023

Molecules

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“…Moreover, an aza-Nazarov cyclization was utilized for the construction of a variety of heterocyclic frameworks such as aminopyrroles [ 25 – 26 ], N -hydroxyoxindoles [ 27 ], indolizines [ 28 ], pyrido[1,2- a ]indoles [ 29 – 30 ], indoles [ 31 – 32 ], and pyrrole-fused heterocyclic tricycles [ 33 ]. The involvement of Nazarov and in particular aza-Nazarov reactions in the cyclization of alkynes that go through metal carbene intermediates has recently been reviewed by Gao and co-workers [ 34 ].…”

Section: Introductionmentioning

confidence: 99%

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

Yagci¹,

Dönmez²,

Şahın³

et al. 2023

Beilstein J. Org. Chem.

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We have developed a catalytic aza-Nazarov reaction of N-acyliminium salts generated in situ from the reaction of a variety of cyclic and acyclic imines with α,β-unsaturated acyl chlorides to afford substituted α-methylene-γ-lactam heterocycles. The reactions proceed effectively in the presence of catalytic (20 mol %) amounts of AgOTf as an anion exchange agent or hydrogen-bond donors such as squaramides and thioureas as anion-binding organocatalysts. The aza-Nazarov cyclization of 3,4-dihydroisoquinolines with α,β-unsaturated acyl chlorides gives tricyclic lactam products 7 in up to 79% yield with full diastereocontrol (dr = >99:1). The use of acyclic imines in a similar catalytic aza-Nazarov reaction with 20 mol % of AgOTf results in the formation of α-methylene-γ-lactam heterocycles 19 in up to 76% yield and with good to high diastereoselectivities (4.3:1 to 16:1). We have demonstrated the scalability of the reaction with a gram-scale example. The relative stereochemistry of the α-methylene-γ-lactam products 19 has been determined via the single-crystal X-ray analysis of lactam 19l. In order to shed light on the details of the reaction mechanism, we have performed carefully designed mechanistic studies which consist of experiments on the effect of β-silicon stabilization, the alkene geometry of the α,β-unsaturated acyl chloride reactants, and adventitious water on the success of the catalytic aza-Nazarov reaction.

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“…Recently, catalytic carbon-carbon bond activation has emerged as a useful tool to build complex molecules rapidly and efficiently [ 6 , 7 , 8 , 9 ]. There are versatile intermediates involved in these reactions, which could be trapped in situ by a second molecule that triggers subsequent tandem reactions [ 10 , 11 , 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Diversified Pyrazolo[3,4-b]pyridine Frameworks from 5-Aminopyrazoles and Alkynyl Aldehydes via Switchable C≡C Bond Activation Approaches

Miao

Liu

et al. 2022

Molecules

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A cascade 6-endo-dig cyclization reaction was developed for the switchable synthesis of halogen and non-halogen-functionalized pyrazolo[3,4-b]pyridines from 5-aminopyrazoles and alkynyl aldehydes via C≡C bond activation with silver, iodine, or NBS. In addition to its wide substrate scope, the reaction showed good functional group tolerance as well as excellent regional selectivity. This new protocol manipulated three natural products, and the arylation, alkynylation, alkenylation, and selenization of iodine-functionalized products. These reactions demonstrated the potential applications of this new method.

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Recent progress towards the transition-metal-catalyzed Nazarov cyclization of alkynes via metal carbenes

Abstract: In recent years, transition-metal-catalyzed tandem cyclization reaction of alkyne, especially involving metal carbene intermediate, has received worthwhile interest as it bypasses the employment of risky and potentially explosive diazo compounds...

Cited by 20 publications

References 135 publications

X-H Bond Insertion Promoted by Heterogeneous Dirhodium Metal–Organic Cage with Alkynes as Safe Carbene Precursors

X-H Bond Insertion Promoted by Heterogeneous Dirhodium Metal–Organic Cage with Alkynes as Safe Carbene Precursors

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

Synthesis of Diversified Pyrazolo[3,4-b]pyridine Frameworks from 5-Aminopyrazoles and Alkynyl Aldehydes via Switchable C≡C Bond Activation Approaches

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