Nickel/NHC‐Catalyzed Enantioselective Cyclization of Pyridones and Pyrimidones with Tethered Alkenes

Shen, Di; Zhang, Wu‐Bin; Li, Zhiyang; Shi, Shi‐Liang; Xu, Youjun

doi:10.1002/adsc.201901582

Cited by 47 publications

(22 citation statements)

References 69 publications

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“…The scope of this C−H annulation is very broad and encompasses various 2‐ and 4‐pyridones as well as uracils and thiopyridones to afford chiral N‐containing heterocycles in an attractive C−H functionalization protocol. A very similar study on the Ni‐NHC‐catalyzed pyridine C−H alkylation was reported [61b] …”

Section: Nickel‐bian‐nhc Complexesmentioning

confidence: 54%

BIAN‐NHC Ligands in Transition‐Metal‐Catalysis: A Perfect Union of Sterically Encumbered, Electronically Tunable N‐Heterocyclic Carbenes?

Chen

Liu

Szostak

2021

Chemistry A European J

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The discovery of NHCs (NHC = N‐heterocyclic carbenes) as ancillary ligands in transition‐metal‐catalysis ranks as one of the most important developments in synthesis and catalysis. It is now well‐recognized that the strong σ‐donating properties of NHCs along with the ease of scaffold modification and a steric shielding of the N‐wingtip substituents around the metal center enable dramatic improvements in catalytic processes, including the discovery of reactions that are not possible using other ancillary ligands. In this context, although the classical NHCs based on imidazolylidene and imidazolinylidene ring systems are now well‐established, recently tremendous progress has been made in the development and catalytic applications of BIAN‐NHC (BIAN = bis(imino)acenaphthene) class of ligands. The enhanced reactivity of BIAN‐NHCs is a direct result of the combination of electronic and steric properties that collectively allow for a major expansion of the scope of catalytic processes that can be accomplished using NHCs. BIAN‐NHC ligands take advantage of (1) the stronger σ‐donation, (2) lower lying LUMO orbitals, (3) the presence of an extended π‐system, (4) the rigid backbone that pushes the N‐wingtip substituents closer to the metal center by buttressing effect, thus resulting in a significantly improved control of the catalytic center and enhanced air‐stability of BIAN‐NHC‐metal complexes at low oxidation state. Acenaphthoquinone as a precursor enables facile scaffold modification, including for the first time the high yielding synthesis of unsymmetrical NHCs with unique catalytic properties. Overall, this results in a highly attractive, easily accessible class of ligands that bring major advances and emerge as a leading practical alternative to classical NHCs in various aspects of catalysis, cross‐coupling and C−H activation endeavors.

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Section: Nickel‐bian‐nhc Complexesmentioning

confidence: 54%

BIAN‐NHC Ligands in Transition‐Metal‐Catalysis: A Perfect Union of Sterically Encumbered, Electronically Tunable N‐Heterocyclic Carbenes?

Chen

Liu

Szostak

2021

Chemistry A European J

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“…For the synthesis of medium ring, a flexible large ring transition state would be involved, rendering the enantioselective control of such a reaction quite challenging 29 – 34 . By surveying a wide range of chiral carbenes, we found that bulky ANIPE, previously developed by Shi and Cramer groups 49 – 51 , was the optimal ligand (see the Supplementary Information for details).…”

Section: Resultsmentioning

confidence: 99%

“…Until recent years, non-formyl C–H bonds were also able to be activated via nickel catalysis to form 7-membered rings (Fig. 1d ) 29 – 34 , while these examples were still limited to reactive C–H bonds such as heterocyclic and polyfluoro-aromatic C–H bonds, and moreover, only scattered substrates were reported with in general low to moderate yield and ee. In contrast, the activation of prevalent and unreactive aromatic C–H bonds towards 7-membered ring synthesis still remains an elusive challenge.…”

Section: Introductionmentioning

confidence: 99%

Construction 7-membered ring via Ni–Al bimetal-enabled C–H cyclization for synthesis of tricyclic imidazoles

Wang

et al. 2021

Nat Commun

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The construction of 7-membered ring via direct C7–H cyclization of benzoimidazoles with alkenes would provide a more atom- and step-economical route to tricyclic imidazoles and derivatives that widely exist in a broad range of bioactive molecules. However, transition metal-catalyzed C–H cyclization for medium-ring synthesis has been limited to reactive C–H bonds, instead, the activation of unreactive C–H bonds towards medium synthesis still remains an elusive challenge. Herein, we report a direct construction of 7-membered rings via Ni–Al co-catalyzed unreactive C7–H cyclization of benzoimidazoles with alkenes, providing a series of tricyclic imidazoles in 40–98% yield and with up to 95:5 er.

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“…[1][2][3] They can undergo various selective transformations to afford a wide range of significant In this context, our group has developed a series of bulky C 2 -symmetric chiral N-heterocyclic carbenes (NHCs), 40 termed ANIPE-and SIPE-type ligands and applied to asymmetric nickel catalysis. [41][42][43][44][45][46][47][48] We recently disclosed the first general asymmetric arylboration of simple ketones to prepare chiral tertiary alcohols using Ni/NHC catalysis and a rare enantioselective η 2 -coordinating activation of ketones. [47,[49][50][51][52][53][54][55][56] Given the importance of chiral secondary alcohols, we became interested in developing asymmetric aldehyde addition of organoborons as a general and efficient approach to prepare chiral secondary alcohols.…”

Section: Introductionmentioning

confidence: 99%

Chemo- and Enantioselective Arylation and Alkenylation of Aldehydes Enabled by Nickel/ N -Heterocyclic Carbene Catalysis

et al. 2022

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We herein report the first highly enantioselective Ni-catalyzed arylation and alkenylation of simple aldehydes using readily available and stable organoboronic esters. This protocol provides various chiral secondary alcohols in high yields and enantioselectivities (up to 97% ee) with a broad scope of substrates, functional groups, and heterocycles. The use of a bulky N-heterocyclic carbene (NHC) ligand for nickel catalyst is the key for high enantiocontrol. The competitive Ni-catalyzed transformations, including Tishchenko reaction, dehydrogenation/hydrogenation reaction, Suzuki-Miyaura couplings, are avoided. The excellent chemoselectivity is probably due to the application of mild base CsF and η 2 -coordination of aldehydes with nickel.

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Nickel/NHC‐Catalyzed Enantioselective Cyclization of Pyridones and Pyrimidones with Tethered Alkenes

Cited by 47 publications

References 69 publications

BIAN‐NHC Ligands in Transition‐Metal‐Catalysis: A Perfect Union of Sterically Encumbered, Electronically Tunable N‐Heterocyclic Carbenes?

BIAN‐NHC Ligands in Transition‐Metal‐Catalysis: A Perfect Union of Sterically Encumbered, Electronically Tunable N‐Heterocyclic Carbenes?

Construction 7-membered ring via Ni–Al bimetal-enabled C–H cyclization for synthesis of tricyclic imidazoles

Chemo- and Enantioselective Arylation and Alkenylation of Aldehydes Enabled by Nickel/ N -Heterocyclic Carbene Catalysis

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