TEMPO-Promoted Mono- and Bisimidation of Tertiary Anilines: Synthesis of Symmetric and Unsymmetric <i>N</i>-Mannich Bases

Xu, Xiu Juan; Amuti, Adila; Wen, Hairuo; Adelibieke, Qiaerbati; Wusiman, Abudureheman

doi:10.1021/acs.joc.2c00700

Cited by 6 publications

(4 citation statements)

References 49 publications

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“…On the basis of these experimental results and our earlier work, [35,36] a tentative mechanism for this coupling reaction is depicted in Scheme 6. Initially, the tertiary amine is activated by NIS to generate the iminium ion intermediate A, while succinimide (NHS) is liberated.…”

Section: Resultssupporting

confidence: 60%

“…Recently, we have developed CÀ N cross-coupling approaches of tertiary amines to form N-Mannich bases using N-halosuccinimide (NXS) [35] or NXS/TEMPO. [36] Mechanistic studies showed that NXS mediated CÀ H bond activation occurs via an ionic pathway, and that the active iminium cation is formed during the reaction. Inspired by this result, we envisioned that the iminium cation might be trapped by a carbon-based nucleophile to achieve a CÀ C cross-coupling reaction, in which the CÀ N coupling adduct (N-Mannich base) might provide a stabilizing effect like an "iminium ion reservoir".…”

Section: Introductionmentioning

confidence: 99%

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NIS/TEMPO‐Promoted Oxidative Cyanation and Nitro‐Mannich Reaction of Tertiary Amines

Yusan,

Amuti,

et al. 2024

Eur J Org Chem

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A metal‐free N‐iodosuccinimde (NIS)/2,2,6,6‐tetramethylpiperidinyloxy (TEMPO)‐promoted protocol was developed for the oxidative α‐cyanation and nitro‐Mannich reaction of tertiary amines via a cross‐dehydrogenative coupling reaction under mild conditions. Several control experiments were performed; the coupling reaction outcomes indicated that the C‐N coupled intermediate (N‐Mannich base) formed from the tertiary amine and NIS had a stabilizing effect on the iminium cation.

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Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

NIS/TEMPO‐Promoted Oxidative Cyanation and Nitro‐Mannich Reaction of Tertiary Amines

Yusan,

Amuti,

et al. 2024

Eur J Org Chem

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“…As examples, electron-rich alkenes can add to the intermediate iminium ion and the formed carbenium ion is trapped by the carbonyl O atom of the N-carbamate protecting group (e.g., Boc), 662 resulting after O-dealkylation in an oxidative annulation 672 of the isoquinoline (Scheme 26a). Amides can act as internal nucleophiles 673 in an enantioselective cyclization in the presence of chiral phosphoric acids (Scheme 26b). 663,674 Further, the iminium ion trapping with cyanide (Scheme 26c), 664,675 azide (Scheme 26h), 669 an allyl silane (Scheme 26d), 665 and alkynes (Scheme 26e and 26g) 666,668,676 was reported.…”

Section: Physical Properties and Reactivitymentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R 1 R 2 N−O • . The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R 1 and R 2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R 1 R 2 N�O + ) or reduced to anions (R 1 R 2 N−O − ), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C−O bonds, allowing for the thermal generation of C radicals through reversible C−O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.

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“…Recently, we reported the iron catalyzed oxidative amidation of tertiary amines using molecular oxygen as the terminal oxidant [25]. Based on our previous work on the oxidative functionalization of tertiary amines [26] and our ongoing research interests in this field, herein, we report a simple protocol for the FeCl 3 catalyzed “synthesis of pyrrolo[2,1‐ a ]isoquinolines” under mild conditions (Scheme 1e).…”

Section: Introductionmentioning

confidence: 99%

Iron‐catalyzed oxidative [3+2] cycloaddition‐aromatization cascade: Synthesis of pyrrolo‐[2,1‐a]isoquinolines

Wen

Liu

Wusiman

2023

Journal of Heterocyclic Chem

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TEMPO-Promoted Mono- and Bisimidation of Tertiary Anilines: Synthesis of Symmetric and Unsymmetric N-Mannich Bases

Cited by 6 publications

References 49 publications

NIS/TEMPO‐Promoted Oxidative Cyanation and Nitro‐Mannich Reaction of Tertiary Amines

NIS/TEMPO‐Promoted Oxidative Cyanation and Nitro‐Mannich Reaction of Tertiary Amines

Organic Synthesis Using Nitroxides

Iron‐catalyzed oxidative [3+2] cycloaddition‐aromatization cascade: Synthesis of pyrrolo‐[2,1‐a]isoquinolines

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