Nitrosocarbonyl–Henry and Denitration Cascade: Synthesis of α-Ketoamides and α-Keto Oximes

Reddy, Mallu Kesava; Mallik, Sumitava; Ramakrishna, Isai; Baidya, Mahiuddin

doi:10.1021/acs.orglett.7b00482

Cited by 26 publications

(10 citation statements)

References 83 publications

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“…In 2017, a distinctive example of the nitrosocarbonyl Henry reaction for the synthesis of α-ketoamides was reported by our group (Scheme 13). 25 When various α-nitro ketones 57 were treated with in situ generated nitrosocarbonyl intermediates 19′ in the presence of quinidine, a cinchona alkaloid, a cascade of α-hydroxyamination followed by water addition-elimination generated intermediate T. Subsequent elimination of nitrite anion from T produced the α-ketoamides 59 in good to excellent yields. Interestingly, the presence of an α-tertiary carbon center in the α-nitro ketone 57 (R 2 ≠ H) gave α-keto oximes 58 as the exclusive product.…”

Section: Short Review Syn Thesismentioning

confidence: 99%

Ambident Reactivity of Nitroso Compounds for Direct Amination and Hydroxylation of Carbonyls

2017

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Functionalization of carbonyls, particularly with a heteroatom subunit, is an important synthetic transformation. Utilization of ambident electrophiles for such a strategy is advantageous because two different heteroatom units can be installed from a single source under judicial reaction conditions. Recently, there have been increased examples for the construction of C–O and C–N bonds using nitroso compounds, a prototype of ambident electrophiles. In this short review, we discuss the advantages and challenges of exploiting nitroso compounds in organic synthesis with specific focus on nitroso aldol type processes for the direct hydroxylation and amination of carbonyl compounds.1 Introduction2 Prime Challenges in Nitroso Aldol Reactions3 Direct Hydroxylation Reactions4 Direct Amination Reactions5 Conclusion and Outlook

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Section: Short Review Syn Thesismentioning

confidence: 99%

Ambident Reactivity of Nitroso Compounds for Direct Amination and Hydroxylation of Carbonyls

2017

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“…α‐Nitroketones, useful bidentate reagents having nitro and keto functionalities, have been recently employed in a range of metal and organocatalytic domino reactions [21] . In 2017, Baidya and co‐workers demonstrated quinidine base catalyzed reaction of hydroxamic acid and α‐nitroketones for the formation of α‐ketoamides and α‐keto oximes with high conversions [22] . The reaction proceeds through nitrosocarbonyl formation, Henry and denitration reaction sequence.…”

Section: Methodsmentioning

confidence: 99%

Efficient Synthesis of α‐Ketothioamides From α‐Nitroketones, Amines or DMF and Elemental Sulfur Under Oxidant‐Free Conditions

Zhang

Yang

et al. 2021

Eur J Org Chem

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We have developed a practical, general protocol for denitration of readily available α‐nitroketones with sulfur and amines to access a broad range of α‐ketothioamides under mild conditions. Such a reaction proceeds under metal‐, oxidant‐, and catalyst‐free conditions to provide synthetically useful α‐ketothioamides. Furthermore, the mild reaction conditions tolerate a wide range of substrates especially for the synthesis of aliphatic α‐ketothioamides which are rarely reported.

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“…They are prototypes of ambident electrophiles and offer unique opportunity to fabricate both C−N and C−O bonds from a single molecule. Over the years, chemists have compiled a reaction compendium consisting of nitrosocarbonyl aldol, [8] Henry, [8l] ene, [9] and diverse types of cycloaddition reactions [10] . With our recent programme on nitrosocarbonyl chemistry, [11] we posited previously unexplored nitrosocarbonyl aldol reaction of deconjugated butyrolactams could be a direct route to make heteroatom‐substituted unsaturated γ ‐lactams (Scheme 1c).…”

Section: Figurementioning

confidence: 99%

Regioselective Nitrosocarbonyl Aldol Reaction of Deconjugated Butyrolactams: Synthesis of γ‐Heterosubstituted α,β‐Unsaturated γ‐Lactams

2021

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The nitrosocarbonyl aldol reaction of deconjugated butyrolactams is developed employing quinidine as organocatalyst. The nitrosocarbonyl species generated in situ from hydroxamic acids react with a variety of deconjugated butyrolactams at room temperature, offering valuable α,β-unsaturated γ-lactams bearing heterosubstituted quaternary carbon center in very high yields. This nitrosocarbonyl aldol reaction is O-selective and proceeds exclusively at the γ-center of deconjugated butyrolactams. The reaction is scalable, accommodates diverse functional groups, and is also effective with azodicarboxylates.γ-Lactams and derivatives thereof, particularly those encompass unsaturation in the ring framework and quaternary carbon center at the γ-position, constitute an important class of heterocycles with eminence in medicinal and pharmaceutical chemistry. [1,2] They represent the core structure of many natural products and biologically significant molecules (Figure 1). [2] They are also widely used as versatile building blocks in organic synthesis towards complex targets. [3] Consequently, devising straightforward strategies to access functionally rich unsaturated γ-lactams remains in the limelight of organic synthesis. [4] In this scenario, among the diverse synthetic endeavours, exploration of nucleophilic reactivity of γ-monosubstituted deconjugated butyrolactams have fetched considerable impetus as they are accessible in diverse substitution patterns from readily available precursors. [5] However, this strategy results in dienolate intermediate which could react with electrophile either through the αor γ-position, leading to a mixture of regioisomeric products (Scheme 1a). Further, such reactivity of deconjugated butyrolactams has majorly been investigated for carbon-carbon bond forming reactions and exploration in carbon-heteroatom bond forming reactions are scarce. In 2017, Mukherjee et al. reported sulfenylation and selenylation of γ-monosubstituted deconjugated butyrolac-[a

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Nitrosocarbonyl–Henry and Denitration Cascade: Synthesis of α-Ketoamides and α-Keto Oximes

Cited by 26 publications

References 83 publications

Ambident Reactivity of Nitroso Compounds for Direct Amination and Hydroxylation of Carbonyls

Ambident Reactivity of Nitroso Compounds for Direct Amination and Hydroxylation of Carbonyls

Efficient Synthesis of α‐Ketothioamides From α‐Nitroketones, Amines or DMF and Elemental Sulfur Under Oxidant‐Free Conditions

Regioselective Nitrosocarbonyl Aldol Reaction of Deconjugated Butyrolactams: Synthesis of γ‐Heterosubstituted α,β‐Unsaturated γ‐Lactams

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