Visible Light Mediated Sulfenylation‐Annulation Cascade of Alkyne Tethered Cyclohexadienones

Nair, Akshay M.; Kumar, Shreemoyee; Volla, Chandra M. R.

doi:10.1002/adsc.201900874

Cited by 38 publications

(26 citation statements)

References 46 publications

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“…Shortly thereafter, Nair et al described a diastereoselective visible-light mediated cascade of cyclohexadienones 278 with alkyne tethers (Scheme 43). [116] Good yields were reported, as was good functional group tolerance. This account relies on Eosin Y as the organic photocatalyst, and boasts an array of thiophenols/thiols as radical precursors, with electron donating and electron withdrawing groups in para-and ortho-positions tolerated for the aromatic thiols.…”

Section: State Of the Artmentioning

confidence: 97%

“…The authors were also able to demonstrate the applicability to gram scale synthesis, and reported favourable green chemistry metrics (atom economy, and efficiency). A publication [117] Shortly thereafter, Nair et al described a diastereoselective visible-light mediated cascade of cyclohexadienones 278 with alkyne tethers (Scheme 43) [116]. Good yields were reported, as was good functional group tolerance.…”

Section: State Of the Artmentioning

confidence: 99%

“…Shortly thereafter, Nair et al described a diastereoselective visible-light mediated cascade of cyclohexadienones 278 with alkyne tethers ( Scheme 43 ) [ 116 ]. Good yields were reported, as was good functional group tolerance.…”

Section: Heterogeneous Substrates: Enynes and Other Mixed Systemsmentioning

confidence: 99%

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Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates

Lynch

Scanlan

2020

Molecules

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Sulfur centered radicals are widely employed in chemical synthesis, in particular for alkene and alkyne hydrothiolation towards thioether bioconjugates. The steadfast radical chain process that enables efficient hydrothiolation has been explored in the context of cascade reactions to furnish complex molecular architectures. The use of thiyl radicals offers a much cheaper and less toxic alternative to the archetypal organotin-based radical methods. This review outlines the development of thiyl radicals as reactive intermediates for initiating carbocyclization cascades. Key developments in cascade cyclization methodology are presented and applications for natural product synthesis are discussed. The review provides a chronological account of the field, beginning in the early seventies up to very recent examples; a span of almost 50 years.

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Section: State Of the Artmentioning

confidence: 97%

Section: State Of the Artmentioning

confidence: 99%

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Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates

Lynch

Scanlan

2020

Molecules

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“…The catalytic potential of Eosin Y in mediating C−S bond formation was further explored by Nair and co‐workers [157] . They have reported a blue light induced, Eosin Y mediated sulfenylation of alkyne tethered cyclohexadienones ( 139 ) followed by cascade annulation via conjugate addition to yield sulfenylated dihydrochromenones ( 140 ).…”

Section: Sulfenylationmentioning

confidence: 99%

“…Finally, abstraction of proton from thiol resulted into desired sulfenylated dihydrochromenones ( 140 ) along with thienyl radical ( 5 F ) (Scheme 47). [157] …”

Section: Sulfenylationmentioning

confidence: 99%

Transition Metal‐Free Sulfenylation of C−H Bonds for C−S Bond Formation in Recent Years: Mechanistic Approach and Promising Future

et al. 2021

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Transition metal‐free sulfenylation of C−H bonds for C−S bond formation has recently emerged as sustainable protocols for the functionalisation of various molecules. Researchers have extensively developed such protocols for the construction of biologically relevant sulfur scaffolds. There has been a gradual shift from metal‐catalyzed to metal‐free C−S bond formation methodologies, because the latter offer environmentally benign and inherently safe access to novel synthetic routes in organic chemistry. The present review offers a dynamic discussion on recent advances in transition metal‐free C−S bond formation via C−H bond functionalization using different surrogate sulfenylating reagents. The review has comprehensively been devoted to radical and ionic mechanistic approaches. Some simple and eco‐friendly reagents for sulfenylation viz. tertbutyl hydrogen peroxide (TBHP), hydrogen peroxide (H2O2), iodine/potassium persulphate (I2/K2S2O8), inorganic bases, strong organic acids, iodine, I2/triphenyl phosphine (PPh3), N‐chlorosuccinamide (NCS), N‐bromosuccinamide (NBS), potassium iodate (KIO3), I2/bovine serum albumin (BSA), tetrabutyl ammonium iodide (TBAI)/HBr and graphene oxide along with their mechanistic approach has been detailed in this review. Moreover, modern methods for the C−S bond formation i. e., biocatalyst, electrochemical and visible light induced sulfenylation, and traditional sulfenylation methodologies have also been incorporated.

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Purple‐Light Promoted Thiol‐ene Reaction of Alkenes

Renzi,

Rusconi,

Ghigo

et al. 2023

Adv Synth Catal

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Here we present a catalyst‐free protocol for the purple light‐mediated anti‐Markovnikov functionalization of alkenes with thiols. Crucial to the generation of the thiyl radical was the formation of a key photo‐active complex. More than 30 thioether products were obtained, demonstrating tolerance towards different functional groups and scalability up to 5 mmol of alkene. Two different reaction conditions have been developed, varying both the solvent and the amount of thiol. Depending on the alkene structure, water can be used as an alternative to dichloromethane as a solvent, thus increasing the sustainability of the whole process.

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Visible Light Mediated Sulfenylation‐Annulation Cascade of Alkyne Tethered Cyclohexadienones

Cited by 38 publications

References 46 publications

Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates

Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates

Transition Metal‐Free Sulfenylation of C−H Bonds for C−S Bond Formation in Recent Years: Mechanistic Approach and Promising Future

Purple‐Light Promoted Thiol‐ene Reaction of Alkenes

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