Organic Synthesis Using Nitroxides

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(16), P. 10302 - 10380

Published: Aug. 14, 2023

Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R1R2N–O•. The spin distribution over nitroxide N and O atoms contributes to thermodynamic stability of these radicals. presence bulky N-substituents R1 R2 prevents radical dimerization, ensuring their kinetic stability. Despite reactivity toward various transient C some nitroxides can be easily stored under air at room temperature. Furthermore, oxidized oxoammonium salts (R1R2N═O+) reduced anions (R1R2N–O–), enabling them act valuable oxidants reductants depending on oxidation state. Therefore, they exhibit interesting across all three states. Due fascinating properties, find extensive applications in diverse fields such biochemistry, medicinal chemistry, materials science, organic synthesis. This review focuses versatile For use other important fields, we will refer several articles. introductory part provides a brief overview history chemistry. Subsequently, key methods for preparing discussed, followed by an examination structural diversity physical properties. main portion this is dedicated reactions, wherein parent corresponding serve active species. It demonstrated that functional groups (such alcohols, amines, enolates, alkanes among others) efficiently oxidized. These oxidations carried out using catalysts combination stoichiometric terminal oxidants. By reducing anions, become effective reagents intriguing Nitroxides possess ability selectively react making useful terminating cascade reactions forming alkoxyamines. Depending structure, alkoxyamines weak C–O bonds, allowing thermal generation through reversible bond cleavage. Such thermally generated participate transformations, discussed end review. application strategy natural product synthesis presented.

Language: Английский

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Constructing Four-Membered Heterocycles by Cycloisomerization

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(7), P. 4101 - 4110

Published: March 10, 2023

Four-membered heterocycles are highly sought after in modern drug discovery as they provide beneficial properties to the target molecules. Despite tremendous efforts by synthetic research community, there is a need for simple and new method incorporate these motifs into design Herein, we reveal cycloisomerization strategy construction of oxetane azetidine rings via metal hydride hydrogen atom transfer/radical polar crossover, which challenging both enthalpically entropically. This suitable synthesizing polysubstituted four-membered heterocycles. mild functional-group tolerant reaction has broad substrate scope, including spiro structure, an important motif research. Various heterocyclic building blocks can be synthesized product derivatization. We also discuss mechanism, focusing on ring formation, deuterium experiments DFT studies.

Language: Английский

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Cobalt-Catalyzed Carbon–Heteroatom Transfer Enables Regioselective Tricomponent 1,4-Carboamination

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(12), P. 8508 - 8519

Published: Feb. 21, 2024

Tricomponent cobalt(salen)-catalyzed carbofunctionalization of unsaturated substrates by radical-polar crossover has the potential to streamline access broad classes heteroatom-functionalized synthetic targets, yet reaction platform remained elusive, despite well-developed analogous hydrofunctionalizations mediated high-valent alkylcobalt intermediates. We report herein development a cobalt(salen) catalytic system that enables carbofunctionalization. The entails tricomponent decarboxylative 1,4-carboamination dienes and provides direct route aromatic allylic amines obviating preformed allylation reagents protection oxidation-sensitive amines. merges acridine photocatalysis with regioselective 1,4-carbofunctionalization facilitates radical polar phases coupling process, revealing critical roles reactants, as well ligand effects nature formal species on chemo- regioselectivity.

Language: Английский

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Controllable skeletal reorganizations in natural product synthesis

Natural Product Reports, Journal Year: 2024, Volume and Issue: 41(2), P. 251 - 272

Published: Jan. 1, 2024

Covering: 2016 to 2023The synthetic chemistry community is always in pursuit of efficient routes natural products. Among the many available general strategies, skeletal reorganization, which involves formation, cleavage, and migration C-C C-heteroatom bonds, stands out as a particularly useful approach for assembly molecular skeletons. In addition, it allows late-stage modification products quick access other family members or unnatural derivatives. This review summarizes syntheses steroid, terpenoid, alkaloid that have been achieved by means this strategy past eight years. Our goal illustrate strategy's potency reveal spectacular human ingenuity demonstrated its use development.

Language: Английский

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Recent advances in the metal-catalyzed asymmetric alkene hydrogenation of cyclic conjugated carbonyl compounds

Organic Chemistry Frontiers, Journal Year: 2024, Volume and Issue: 11(10), P. 2934 - 2953

Published: Jan. 1, 2024

This review summarizes the recent advances (2016–2023) in stereoselective metal-catalyzed hydrogenation of cyclic α,β-unsaturated ketones, lactams and lactones since considerable developments were made. Where possible application these methodologies synthesis is outlined.

Language: Английский

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Arylamine synthesis enabled by a photocatalytic skeletal-editing dehydrogenative aromatization strategy

Chem Catalysis, Journal Year: 2024, Volume and Issue: 4(1), P. 100873 - 100873

Published: Jan. 1, 2024

Language: Английский

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Total Synthesis of (−)-Retigeranic Acid A: A Reductive Skeletal Rearrangement Strategy

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(22), P. 11927 - 11932

Published: May 24, 2023

The asymmetric total synthesis of (−)-retigeranic acid A was described, which relies on a crucial reductive skeletal rearrangement cascade for the controllable assembly diverse angular triquinane subunits. Taken together with an intramolecular Michael/aldol cyclization, ODI-[5 + 2] cycloaddition/pinacol cascade, Wolff ring contraction and stereoselective HAT reduction, our synthetic approach has enabled access to in concise practical manner.

Language: Английский

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Aldehydes as O-Nucleophiles in Cobalt Hydride Hydrogen Atom Transfer Catalysis: Overriding the Innate Somophilicity

Organic Letters, Journal Year: 2023, Volume and Issue: 25(5), P. 889 - 894

Published: Feb. 1, 2023

In metal hydride-catalyzed alkene hydrofunctionalization reactions via hydrogen atom transfer, simple carbonyl groups have been well-recognized as good somophiles at the carbon for C-C bond formation. Here we report an alternative pathway exploring O-nucleophile to make new C-O bonds during CoH-catalyzed oxidative cyclization of alkenyl aldehydes. This reaction provides a rapid, mild, modular, and stereoselective (up >20:1) entry saturated O-heterocycles nucleophilic trapping in situ-formed oxocarbenium intermediate. The key overriding carbonyl's innate somophilicity was found be promoting formation organocobalt species suppressing radical exchange.

Language: Английский

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Enantiocontrolled Total Synthesis of (−)-Retigeranic Acid A

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(25), P. 13549 - 13555

Published: June 12, 2023

The asymmetric total synthesis of (-)-retigeranic acid A has been realized. key features the current include (1) a Pt-catalyzed Conia-ene 5-exo-dig cyclization enolyne to establish quaternary stereochemical center C-10 (D/E ring), (2) an intramolecular diastereoselective Prins construct trans-hydrindane backbone (A/B and (3) late-stage Fe-mediated hydrogen atom transfer (HAT) Baldwin-disfavored 5-endo-trig radical rapidly assemble vicinal centers core structure (C ring).

Language: Английский

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A Homo‐Mannich Reaction Strategy Enables Collective Access to Ibophyllidine, Aspidosperma, Kopsia, and Melodinus Alkaloids

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(37)

Published: July 25, 2023

We report here a homo-Mannich reaction of cyclopropanol with an iminium ion, generated by asymmetric allylic dearomatization indole, to construct tricyclic hydrocarbazole core, which is shared variety monoterpenoid indole alkaloids across families. Through this approach, all-carbon quaternary stereogenic center as well allyl and ketone group were installed. Using functionalized the structural platform, D ring E rings different sizes (i.e., five-, six-, seven-membered) successively or simultaneously assembled, leading collective synthesis seven belonging ibophyllidine, Aspidosperma, Kopsia, Melodinus alkaloid

Language: Английский

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