Photochemically and thermally induced free-radical reactions of .alpha.,.beta.-epoxy ketones with tributyltin hydride: selective C.alpha.-O bond cleavage of oxiranylmethyl radicals derived from .alpha.,.beta.-epoxy ketones

Hasegawa, Eietsu; Ishiyama, Kenyuki; Kato, T.; Horaguchi, Takaaki; Shimizu, Takahachi; Tanaka, Shoji; Yamashita, Yoshiro

doi:10.1021/jo00046a016

Cited by 54 publications

(12 citation statements)

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“…When employing [D 2 ]Hantzsch ester [D 2 ]‐ 14 as hydrogen donor, up to 60 % deuteration of the expected α‐carbonyl position was observed. Moreover, in analogy to a recent photoredox allylation,7, 29 we were able to trap the intermediary α‐carbonyl radical with allyltributylstannane (Scheme ).…”

Section: Methodsmentioning

confidence: 97%

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A Cooperative Hydrogen‐Bond‐Promoted Organophotoredox Catalysis Strategy for Highly Diastereoselective, Reductive Enone Cyclization

Neumann

Zeitler

2013

Chemistry A European J

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Mild and efficient methods for catalytic CÀC bond formations are of great importance to both academic and industrial research, and green and sustainable processes pose an additional major challenge for synthetic organic chemists. Over the last decade, organocatalysis has successfully started to seize the mantle and especially multicatalysis conceptscombining robust, metal-free catalysts-allow access to complex (asymmetric) structures and many formerly elusive transformations. [1] Only recently has the combination of organocatalytic activation modes with other sustainable methods begun to evolve. [2] In this context, in particular the merger with visible-light photoredox chemistry [3] has emerged as a powerful approach, as was evidenced by pioneering examples by the groups of MacMillan, [4] Rueping, [5] and Rovis. [6] Secondary amine and NHC catalysis were successfully combined in synergistic processes with [RuA C H T U N G T R E N N U N G (bpy) 3 ] 2 + -mediated photoredox catalysis. Although metal-complex-promoted photocatalysis, which is often based on expensive and scarce Ru and Ir complexes, [7] is still mandatory for some applications, we have recently developed a photoredox protocol demonstrating the applicability of Eosin Y as a potent metal-free surrogate for [RuA C H T U N G T R E N N U N G (bpy) 3 ] 2 + . [8] In this context, we could also show that simple organic photoredox catalysts can participate in highly enantioselective synergistic transformations with two catalytic cycles working perfectly in concert. [8a] Continuing this theme, we questioned if the photoredox multicatalysis strategy could be extended to other organocatalytic activation modes.Apart from the above-mentioned successful examples to combine photoredox catalysis with amine and NHC catalysis, respectively (Scheme 1), a merger with metal-free carbonyl activation has not yet been described. As hydrogen- [a] Dr.

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Section: Methodsmentioning

confidence: 97%

“…served. Moreover, in analogy to a recent photoredox allylation, [7,29] we were able to trap the intermediary a-carbonyl radical with allyltributylstannane (Scheme 5).…”

mentioning

confidence: 96%

A Cooperative Hydrogen‐Bond‐Promoted Organophotoredox Catalysis Strategy for Highly Diastereoselective, Reductive Enone Cyclization

Neumann

Zeitler

2013

Chemistry A European J

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“…5 Epoxidation of 8 with aqueous NaOH and H 2 O 2 (95%) followed by regioselective ring cleavage of the resulting oxirane 9 with tributyltin hydride gave the racemic b-hydroxy ketone 10b in quantitative yield. 6,7 Despite its high efficiency, the synthesis of 10b via Weinreb amide 7 is not suitable for the synthesis of optically active compounds. We therefore developed an alternative strategy that commences from 3-methylcatechol.…”

Section: Scheme 1 Retrosynthetic Analysis Ofmentioning

confidence: 99%

Synthesis of the α,β-Unsaturated δ-Lactones (+)-Anhydrocalopin and (+)-Dehydrocalopin

Ebel¹,

Zeitler²,

Steglich³

2003

Synthesis

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“…Such reactions have been recognized as important processes not only in thermal but also in photochemical transformations. Single electron transfer (SET) induced ring opening reactions of epoxides and α-epoxyketones have demonstrated C-C and C-O bond cleavages through photo-induced electron transfer by various electron donors such as triethylamine (TEA), [21] tribenzylamine (TBA) [20] and 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI) [22-24] or thermally induced single electron transfer by electron donating compounds such as samarium diiodide, [25] tributyltin hydride [26] and bis(cyclopentadienyl)titanium(III) chloride. [27] Ring opening reactions of epoxides and α-epoxyketones have also occurred thermally or photochemically by the presence of various electron acceptors.…”

Section: Introductionmentioning

confidence: 99%

Photosonochemical catalytic ring opening of α-epoxyketones

Memarian¹,

Saffar‐Teluri²

2007

Beilstein J. Org. Chem.

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Photochemically and thermally induced free-radical reactions of .alpha.,.beta.-epoxy ketones with tributyltin hydride: selective C.alpha.-O bond cleavage of oxiranylmethyl radicals derived from .alpha.,.beta.-epoxy ketones

Cited by 54 publications

References 0 publications

A Cooperative Hydrogen‐Bond‐Promoted Organophotoredox Catalysis Strategy for Highly Diastereoselective, Reductive Enone Cyclization

A Cooperative Hydrogen‐Bond‐Promoted Organophotoredox Catalysis Strategy for Highly Diastereoselective, Reductive Enone Cyclization

Synthesis of the α,β-Unsaturated δ-Lactones (+)-Anhydrocalopin and (+)-Dehydrocalopin

Photosonochemical catalytic ring opening of α-epoxyketones

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