<i>O</i>-Benzoylhydroxylamines as Alkyl Nitrene Precursors: Synthesis of Saturated N-Heterocycles from Primary Amines

Noda, Hidetoshi; Asada, Yasuko; Shibasaki, Masakatsu

doi:10.1021/acs.orglett.0c02842

Cited by 30 publications

(19 citation statements)

References 51 publications

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“…The progress of alkyl nitrenes in synthetic chemistry has been sluggish [73,74] . Nevertheless, a number of suitable combinations of catalysts and nitrene precursors has increased during the last decade [75–79] …”

Section: Intramolecular Nitrene Transfersmentioning

confidence: 99%

Catalyst‐Controlled Chemoselective Nitrene Transfers

Noda

Tang

Shibasaki

2021

Helvetica Chimica Acta

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Transition metal catalyzed nitrene transfers provide nitrogen containing compounds through C−H bond insertion, aziridination of olefins, and other types of reactions. Given the importance of these compounds in natural products and pharmaceuticals, tremendous efforts have been devoted to the development of efficient and reliable catalytic methods. In particular, the last decade has seen a remarkable progress in catalyst‐controlled chemoselective nitrene transfers, wherein different products can be obtained from a single substrate by the choice of catalyst. This Minireview covers this important and emerging area. We explain the principle of catalyst‐controlled synthesis, followed by highlighting literature examples for intra‐ and intermolecular reactions with an emphasis on the understanding of the nature of reactive intermediates and the strategy needed to realize selectivity. Finally, future directions are discussed based on the literature precedents.

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Section: Intramolecular Nitrene Transfersmentioning

confidence: 99%

Catalyst‐Controlled Chemoselective Nitrene Transfers

Noda

Tang

Shibasaki

2021

Helvetica Chimica Acta

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“…Alkyl nitrenes having C-H bond(s) next to the nitrogen are known to be unstable 55) (Chart 11c), and their use in organic synthesis has been underexplored. [56][57][58][59][60][61][62] When suitably substituted isoxazolidin-5-ones were subjected to a catalytic amount of Rh 2 (esp) 2 in HFIP, the expected spirocyclic β-prolines were exclusively formed 63) (Fig. 6).…”

Section: Rhodium-catalyzed C(sp3)-h Insertion For the Synthesis Of Spirocyclic β-Prolines And β-Homoprolinesmentioning

confidence: 99%

Imbuing an Old Heterocycle with the Power of Modern Catalysis: An Isoxazolidin-5-one Story

Noda

2021

CHEMICAL & PHARMACEUTICAL BULLETIN

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Isoxazolidin-5-ones have been regarded as β-amino acid surrogates owing to their labile N-O bond. While many efforts have been devoted to the catalytic enantioselective synthesis of the core of this heterocycle, its further transformation has been less explored, especially in the context of catalysis. This review summarizes the author's research on the development of catalytic reactions using isoxazolidin-5-ones as substrates. Asymmetric catalysis has proven effective for C-C bond formation at the carbonyl α-carbon. Catalytic asymmetric allylation and direct Mannich-type reactions have been developed. Further, the resulting products have been readily converted into the corresponding quaternary β 2,2 -amino acids. Moreover, isoxazolidin-5-ones have been identified as alkyl nitrene precursors in the presence of a suitable metal catalyst. The generated metallonitrene undergoes either the electrophilic amination of the aromatic ring or aliphatic C-H insertion, affording a series of cyclic β-amino acids. A remarkable difference in chemoselectivity between rhodium and copper alkyl nitrenes has also been demonstrated, highlighting the unique nature of the underexplored reactive intermediates. The various linear and cyclic β-amino acids obtained through the study are likely to find great utility in a broad range of chemical sciences.

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“…3,4 In practice, electron-withdrawing groups, such as N-sulfonyl substituents, are typically required to activate aminating reagents for C-H functionalization and methods to elaborate the resulting sulfonamides to more complex nitrogen-containing molecules are limited. 5,6 We recently introduced N-aminopyridinium salts as bifunctional reagents in C-H amination chemistry. 7 The combination of a nucleophilic N-amino group and a reductively activatable N-N bond 8 provided a platform to couple C-H amination with C-N cross coupling to achieve formal nitrene transfer to benzylic C-H bonds.…”

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confidence: 99%

Diversification of Amidyl Radical Intermediates Derived from C–H Aminopyridylation

Maity¹,

Roychowdhury²,

Herrera³

et al. 2022

Preprint

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C–H amination chemistry promises to streamline access to nitrogen-containing fine chemicals. The typical need for N-activating substituents — such of N-sulfonyl groups, which are challenging to remove and difficult to engage in synthetic elaboration — limits synthetic utility. Here, we demonstrate that N-benzylaminopyridinium species, generated by C–H aminopyridylation, provide a platform for synthetic elaboration via reductive N–N bond activation to unveil electrophilic N-centered radicals. These reactive intermediates can be trapped either via anti-Markovnikov olefin carboamination to provide access to tetrahydroisoquinolines, which are important heterocycles in molecular therapeutics, or via aza-Rubottom chemistry with silyl enol ethers to provide alpha-amino ketones. This approach broadens the synthetic utility of N-alkylaminopyridinium intermediates and demonstrates a new approach to C–H amination with synthetically addressable, bifunctional reagents.

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O-Benzoylhydroxylamines as Alkyl Nitrene Precursors: Synthesis of Saturated N-Heterocycles from Primary Amines

Cited by 30 publications

References 51 publications

Catalyst‐Controlled Chemoselective Nitrene Transfers

Catalyst‐Controlled Chemoselective Nitrene Transfers

Imbuing an Old Heterocycle with the Power of Modern Catalysis: An Isoxazolidin-5-one Story

Diversification of Amidyl Radical Intermediates Derived from C–H Aminopyridylation

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