Chiral Organotin Hydride Catalyzed Enantioselective Radical Cyclization of Aldehydes

Shirakawa, Seiji; Usui, Asuka; Kan, S. B. Jennifer; Maruoka, Keiji

doi:10.1002/ajoc.201300138

Cited by 17 publications

(8 citation statements)

References 64 publications

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“…Four decades later, to develop a successful catalytic variant, the Maruoka group proposed an enantioselective radical cyclization catalyzed by organotin hydride using stoichiometric Ph2SiH2 as a reducing agent (Scheme 53). 121 Addition of chiral stannyl radical to aldehyde connected to an internal alkene 2.1. Thiyl-radical-mediated organic transformations have attracted increasing importance which makes them powerful intermediates.…”

Section: Asymmetric Catalysis Involving Chiral Thiyl and Stannyl Radi...mentioning

confidence: 99%

“…Two decades later, to develop a successful catalytic variant, the Maruoka group proposed an enantioselective radical cyclization catalyzed by organotin hydride using stoichiometric Ph 2 SiH 2 as a reducing agent (Scheme ). Addition of chiral stannyl radical to aldehyde connected to an internal alkene 2.1.101 afforded heterocycle 2.1.102 in good yield albeit with moderate enantio- and diastereoselectivity (53% ee, 87:13 dr). The initiation step is assumed to arise from AIBN, and then addition of the chiral stannyl radical to aldehyde moiety generates O -stannyl ketyl radical 2.1.101A .…”

Section: Organocatalyzed Enantioselective Radical Reactionsmentioning

confidence: 99%

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Enantioselective Radical Reactions Using Chiral Catalysts

Mondal¹,

et al. 2022

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Scheme 24 Enantioselective Radical Hydroacylation of Enals with α-Ketoacids byMerging Photoredox Catalysis with Amine Catalysis.Jang et al. exploited enantioselective tandem Michael addition/oxyamination of α,β-unsaturated aldehydes by combining asymmetric iminium catalysis using organocatalyst with photoinduced SOMO catalysis using N719/TiO2. 60 Here, TiO2 acts as a second cooperative photocatalyst along with Ru photocatalyst N719 which bound to the latter, increases the enantio-and diastereoselectivity of the process. Adamantane carboxylic acid (30 mol%) was used as an additive which promotes formation of iminium ion 2.1.48A from aldehyde 2.1.48 and chiral amine catalyst. This iminium intermediate then reacts with diethyl malonate to provide intermediate 2.1.48B which either undergoes hydrolysis to form β-substituted aldehyde 2.1.50 or photo-oxidation by the photoexcited Ru(II) dye to form enamine radical 2.1.48C. Subsequent addition of TEMPO to radical intermediate 2.1.48BC followed by hydrolysis afforded the desired product 2.1.49 (Scheme 25). This mechanism is obeying to a polar/radical crossover sequence where the first stereocontrol arises from the addition of the malonate.Recently, Bach group reported promising preliminary results of enantioselective [2+2] photocycloaddition of cinnamaldehyde in the presence of ruthenium photocatalyst and proline derived organocatalyst. 61

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Section: Asymmetric Catalysis Involving Chiral Thiyl and Stannyl Radi...mentioning

confidence: 99%

Section: Organocatalyzed Enantioselective Radical Reactionsmentioning

confidence: 99%

Enantioselective Radical Reactions Using Chiral Catalysts

Mondal¹,

et al. 2022

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“…Maruoka et al have reported chiral organotin hydride catalyzed enantioselective radical cyclization of aldehydes. [15] This is a significant advancement in chiral organotin hydride based radical reductions as most of the reported methodologies require stoichiometric amount of the chiral tin reagent. Also, organotin reagents only engage in atom abstraction process and are not involved in bond forming process.…”

Section: Chiral Hydrogen Atom Transfer Reagentsmentioning

confidence: 99%

Stereoselective Hydrogen Atom Transfer in Free Radical Reactions

Subramanian

Sibi

2023

Asian J Org Chem

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Hydrogen atom transfer (HAT) is one of the important class of radical reactions. Although extensive research into this elementary step has resulted in the discovery of many compounds capable of functioning as HAT reagents, synthetic methods available to control the stereoselectivity of the HAT process remains challenging. This mini review outlines how small molecule chiral HAT reagents and catalysts were used to achieve stereoselectivity (diastereoselectivity and enantioselectivity) in free radical reactions. The review also focuses on the recent surge in photoenzymatic catalysis to achieve efficient HAT reactions.

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“…The use of chiral radicals as a catalyst for controlling the stereochemistry of radical reactions has been rarely explored. A chiral organotin hydride was applied to the enantioselective radical cyclization by Maruoka's group (Scheme ) . In the presence of chiral organotin 81 (10 mol %), treatment of aldehyde 80 with Ph 2 SiH 2 and AIBN in a 1:1 benzene/EtOH mixture at 80 °C gave the cyclized product 82 in 75 % yield with moderate diastereo‐ and enantioselectivity.…”

Section: Reactions Using Chiral Organotin Hydride and Chiral Thiolsmentioning

confidence: 99%

Progress in Enantioselective Radical Cyclizations

Miyabe

Kawashima

Yoshioka

et al. 2017

Chemistry A European J

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The control of stereoselectivity in radical reactions is of great importance to organic synthesis. Hence, new concepts and strategies for controlling stereochemistry of radical reactions are emerging continuously. This Review highlights the recent remarkable progress in enantioselective radical cyclization reactions. Initially, the chiral Lewis acid-catalyzed method became a field of central importance for enantioselective radical cyclizations. In recent years, significant progress has been made in enantioselective organocatalysis. In contrast to intermolecular reactions, the successful examples for enantioselective radical cyclizations are still limited. In this Review, the radical cyclizations controlled by chiral Lewis acids, chiral metallic reagents, chiral imidazolidinone catalysts, chiral non-covalent organocatalysts, and chiral thiols are summarized.

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Chiral Organotin Hydride Catalyzed Enantioselective Radical Cyclization of Aldehydes

Cited by 17 publications

References 64 publications

Enantioselective Radical Reactions Using Chiral Catalysts

Enantioselective Radical Reactions Using Chiral Catalysts

Stereoselective Hydrogen Atom Transfer in Free Radical Reactions

Progress in Enantioselective Radical Cyclizations

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