A practical oxidative C–H functionalization of N-carbamoyl tetrahydro-β-carbolines with diverse potassium trifluoroborates

Sun, Yan; Wang, Gang; Chen, Jiayu; Liu, Chang; Cai, Manqi; Zhu, Rongxiu; Huang, Hongtao; Li, Wei; Liu, Lei

doi:10.1039/c6ob01171c

Cited by 16 publications

(8 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Tetrahydrocarbazoles, tetrahydro-b-carbolines (THbCs) and tetrahydro-g-carbolines (THgCs) with attractive pharmacological potentials, [16] are common core motifs in natural products and pharmaceuticals. [17] These scaffolds have become an interesting starting point for direct functionalization in organic and medicinal chemistry.…”

Section: Abstract: Catalytic Oxidative Coupling Cyclization; Benzofurmentioning

confidence: 99%

Catalytic Oxidative Coupling Cyclization for Construction of Benzofuroindolenines under Mild Reaction Conditions

Lin

Zhang

et al. 2018

Adv Synth Catal

View full text Add to dashboard Cite

show abstract

Section: Abstract: Catalytic Oxidative Coupling Cyclization; Benzofurmentioning

confidence: 99%

Catalytic Oxidative Coupling Cyclization for Construction of Benzofuroindolenines under Mild Reaction Conditions

Lin

Zhang

et al. 2018

Adv Synth Catal

View full text Add to dashboard Cite

show abstract

“…Among THCs, tetrahydro-β-carbolines (THβCs) and tetrahydro-γ-carbolines (THγCs) possess interesting pharmacological profiles, , indicating that they are promising building blocks for the rapid synthesis of complex scaffolds in drug discovery and development. , Therefore, functionalization of THCs has become an intense subject in chemical research . For example, Liu et al reported a practical metal-free oxidative C–H functionalization of N -carbamoyl THCs in the α-position . Kozmin and co-workers demonstrated an efficient synthetic strategy to a skeletally diverse chemical library of indoloquinolizidines .…”

mentioning

confidence: 99%

Biomimetic Oxidative Coupling Cyclization Enabling Rapid Construction of Isochromanoindolenines

Lin

Liu

et al. 2018

Org. Lett.

View full text Add to dashboard Cite

Herein, we report a biomimetic oxidative coupling cyclization strategy for the highly efficient functionalization of tetrahydrocarbolines (THCs). This process enables rapid access to complex isochromanoindolenine scaffolds in moderate to excellent yields. The reaction proceeds smoothly and rapidly (complete within minutes) in an open flask. This operationally simple protocol is scalable and compatible with a wide range of functional groups. Late-stage functionalization of a pharmacologically relevant molecule is also demonstrated.

show abstract

“…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), resulting after O -dealkylation in an oxidative annulation of the isoquinoline (Scheme a). Amides can act as internal nucleophiles in an enantioselective cyclization in the presence of chiral phosphoric acids (Scheme b). , Further, the iminium ion trapping with cyanide (Scheme c), , azide (Scheme h), an allyl silane (Scheme d), and alkynes (Scheme e and g) ,, was reported. A very elegant approach was presented by the group of García Mancheño using diazomethane derivatives as nucleophiles, leading to a ring expansion to obtain valuable 3-benzazepines (Scheme f) .…”

Section: Oxidation Reactionsmentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

View full text Add to dashboard Cite

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.

show abstract

A practical oxidative C–H functionalization of N-carbamoyl tetrahydro-β-carbolines with diverse potassium trifluoroborates

Cited by 16 publications

References 84 publications

Catalytic Oxidative Coupling Cyclization for Construction of Benzofuroindolenines under Mild Reaction Conditions

Catalytic Oxidative Coupling Cyclization for Construction of Benzofuroindolenines under Mild Reaction Conditions

Biomimetic Oxidative Coupling Cyclization Enabling Rapid Construction of Isochromanoindolenines

Organic Synthesis Using Nitroxides

Contact Info

Product

Resources

About