Oxoammonium Salt-Promoted Multifunctionalization of Saturated Cyclic Amines Based On β-Oxo Cyclic Iminium Ion Intermediates

He, Yan; Liu, Qimeng; Yang, Jincai; Zheng, Zhi; Chai, Guo-Li; Zhang, Xinying; Fan, Xuesen

doi:10.1021/acs.orglett.2c03253

Cited by 13 publications

(5 citation statements)

References 57 publications

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“…With tert -butylhydroperoxide (TBHP), ring contraction to 82 is observed, and in combination with a base, the TEMPO ester 75 finally results (Scheme h and g) . With ammonium thiocyanate in EtOH, the intermediate 74 gets converted to the bicycle 76 , and with KSCN and aminoethanethiol, the tricycle 77 is formed (Scheme h) …”

Section: Oxidation Reactionsmentioning

confidence: 99%

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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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Section: Oxidation Reactionsmentioning

confidence: 99%

“…735 With ammonium thiocyanate in EtOH, the intermediate 74 gets converted to the bicycle 76, and with KSCN and aminoethanethiol, the tricycle 77 is formed (Scheme 30h). 736…”

Section: Physical Properties and Reactivitymentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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“…11 b Then, B undergoes nucleophilic addition with 4-OH-TEMPO + to afford the β-4-OH-TEMPO-decorated iminium ion i . On the one hand, intermediate i is captured by − NCS, the isomer of − SCN, 13 to give difunctionalized piperidine C . Then, C may react with water and undergo intramolecular nucleophilic substitution to provide product 3a .…”

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confidence: 99%

“…11b Then, B undergoes nucleophilic addition with 4-OH-TEMPO + to afford the b-4-OH-TEMPO-decorated iminium ion i. On the one hand, intermediate i is captured by À NCS, the isomer of À SCN, 13 to give difunctionalized piperidine C. Then, C may react with water and undergo intramolecular nucleophilic substitution to provide product 3a. Alternatively, C may react with NH 3 and undergo intramolecular nucleophilic substitution to provide intermediate E, which can be hydrolyzed into product 3a.…”

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confidence: 99%

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Oxoammonium salt-promoted diverse functionalization of saturated cyclic amines with dinucleophiles

Liu

Yang

et al. 2023

Chem. Commun.

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Catalytic and Aerobic Oxidative C−H Annulation Reaction of Saturated Cyclic Amines for Synthesis of Dipyrroloquinolines

et al. 2023

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With the aim of providing an efficient platform for the one-step construction of nitrogencontaining polycyclic frameworks, we report a heterogeneous platinum-catalyzed oxidative α,β-C-(sp 3 )À H dual functionalization of saturated cyclic amines. This method involves a tandem oxidative dehydrogenation/hetero Diels-Alder reaction under aerobic mild conditions, providing tetracyclic octahydro-dipyrroloquinoline frameworks in good yields. The reaction was applied to the synthesis of natural products incargranine B aglycone and seneciobipyrrolidine in one step. This study provides efficient and rapid access to nitrogen-containing fused tetracyclic compounds in a highly atomeconomical fashion.

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Oxoammonium Salt-Promoted Multifunctionalization of Saturated Cyclic Amines Based On β-Oxo Cyclic Iminium Ion Intermediates

Cited by 13 publications

References 57 publications

Organic Synthesis Using Nitroxides

Organic Synthesis Using Nitroxides

Oxoammonium salt-promoted diverse functionalization of saturated cyclic amines with dinucleophiles

Catalytic and Aerobic Oxidative C−H Annulation Reaction of Saturated Cyclic Amines for Synthesis of Dipyrroloquinolines

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