Photocatalytic Synthesis of γ-Lactones from Alkenes: High-Resolution Mass Spectrometry as a Tool To Study Photoredox Reactions

Triandafillidi, Ierasia; Kokotou, Maroula G.; Kokotos, Christoforos G.

doi:10.1021/acs.orglett.7b03256

Cited by 91 publications

(62 citation statements)

References 68 publications

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“…By using eosin B as photocatalyst, bases, including NaHCO 3 , K 2 CO 3 , Cs 2 CO 3 , K 3 PO 4 , 2,6-lutidine, TBD DBU, TMG, and Et 3 N were screened, respectively (entries [8][9][10][11][12][13][14][15][16]. The results indicated that DABCO was superior to the others (entry 6 vs entries [8][9][10][11][12][13][14][15][16]. Surprisingly, the yield of 3 a was significantly improved to 70% when the reaction was conducted in open air by using eosin B (5 mol%) and sub-stoichiometric amounts of DABCO (50 mol%) (entry 17).…”

Section: Resultsmentioning

confidence: 99%

“…[14] The recently developed visible-light photoredox catalysts include ruthenium and iridium polypyridyl complexes and organic dyes, which efficiently facilitated the conversion of visible-light into chemical energy under extremely mild conditions. [15] In spite of the excellent photocatalytic properties of ruthenium and iridium polypyridyl complexes in organic synthesis, the metal complexes are usually expensive and potentially toxic. In contrast, organic dyes are an attractive alternative to the transition metal complexes as photoredox catalysis in that they are usually less expensive, less toxic, and easier to handle.…”

Section: Introductionmentioning

confidence: 99%

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A Visible‐Light‐Promoted Metal‐Free Strategy towards Arylphosphonates: Organic‐Dye‐Catalyzed Phosphorylation of Arylhydrazines with Trialkylphosphites

Chen

Wei

et al. 2018

Adv Synth Catal

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A visible-light-induced metal-free catalytic system was developed for the synthesis of arylphosphonates starting from arylhydrazines and trialkylphosphites. By using the inexpensive eosin B as catalyst, substoichiometric amounts of DABCO, and ambient air as oxidant, diverse arylphosphonates were obtained under visible-light irradiation. Notably, this catalytic system is suitable for gram-scale reaction by utilizing sunlight as an illumination source.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Visible‐Light‐Promoted Metal‐Free Strategy towards Arylphosphonates: Organic‐Dye‐Catalyzed Phosphorylation of Arylhydrazines with Trialkylphosphites

Chen

Wei

et al. 2018

Adv Synth Catal

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“…If we attempted to employ styrene as the olefin partner, in the exact same conditions, we could only observe polymerization events to occur (Scheme A). This is in accordance with our previous postulation and findings that a different mechanism is in place if an aryl versus an alkyl substituent on the olefin is employed and whether sodium ascorbate is added or not . To verify this, we performed the reaction as described in literature, and indeed, the product bearing the ether was obtained in 78 % yield (Scheme B).…”

Section: Resultsmentioning

confidence: 99%

Expanding the Scope of Photocatalysis: Atom Transfer Radical Addition of Bromoacetonitrile to Aliphatic Olefins

2018

Self Cite

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An efficient photocatalyzed bromocyanomethylation of alkenes is reported. Among a range of organocatalysts and metal complexes, Ir(ppy)3 proved to be the best photocatalyst in promoting the addition of BrCH2CN to olefins. This photocatalytic atom transfer protocol can be expanded into a wide substrate scope of aliphatic olefins bearing various functional groups, leading to the corresponding products in good to excellent yields. In addition, linchpin catalysis was developed, since the bromo group can undergo further transformation into useful functional groups, such as the synthesis of amino acids.

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“…Recently, Kokotos and co-workers published a visible light photoredox catalyzed lactone formation from iodoacetic acid and alkenes [29] (Scheme 1). In addition, it has been shown that monochloroacetic acid can be reduced by hydrated electrons [30,31].…”

Section: Introductionmentioning

confidence: 99%

Visible-light-induced addition of carboxymethanide to styrene from monochloroacetic acid

Vliet¹,

Leeuwen²,

Brouwer³

et al. 2020

Beilstein J. Org. Chem.

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Where monochloroacetic acid is widely used as a starting material for the synthesis of relevant groups of compounds, many of these synthetic procedures are based on nucleophilic substitution of the carbon chlorine bond. Oxidative or reductive activation of monochloroacetic acid results in radical intermediates, leading to reactivity different from the traditional reactivity of this compound. Here, we investigated the possibility of applying monochloroacetic acid as a substrate for photoredox catalysis with styrene to directly produce γ-phenyl-γ-butyrolactone. Instead of using nucleophilic substitution, we cleaved the carbon chlorine bond by single-electron reduction, creating a radical species. We observed that the reaction works best in nonpolar solvents. The reaction does not go to full conversion, but selectively forms γ-phenyl-γ-butyrolactone and 4-chloro-4-phenylbutanoic acid. Over time the catalyst precipitates from solution (perhaps in a decomposed form in case of fac-[Ir(ppy)3]), which was proven by mass spectrometry and EPR spectroscopy for one of the catalysts (N,N-5,10-di(2-naphthalene)-5,10-dihydrophenazine) used in this work. The generation of HCl resulting from lactone formation could be an additional problem for organometallic photoredox catalysts used in this reaction. In an attempt to trap one of the radical intermediates with TEMPO, we observed a compound indicating the generation of a chloromethyl radical.

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Photocatalytic Synthesis of γ-Lactones from Alkenes: High-Resolution Mass Spectrometry as a Tool To Study Photoredox Reactions

Cited by 91 publications

References 68 publications

A Visible‐Light‐Promoted Metal‐Free Strategy towards Arylphosphonates: Organic‐Dye‐Catalyzed Phosphorylation of Arylhydrazines with Trialkylphosphites

A Visible‐Light‐Promoted Metal‐Free Strategy towards Arylphosphonates: Organic‐Dye‐Catalyzed Phosphorylation of Arylhydrazines with Trialkylphosphites

Expanding the Scope of Photocatalysis: Atom Transfer Radical Addition of Bromoacetonitrile to Aliphatic Olefins

Visible-light-induced addition of carboxymethanide to styrene from monochloroacetic acid

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