Realizing the Photoene Reaction with Alkenes under Visible Light Irradiation and Bypassing the Favored [2 + 2]-Photocycloaddition

Ahuja, Sapna; Raghunathan, Ramya; Kumarasamy, Elango; Jockusch, Steffen; Sivaguru, Jayaraman

doi:10.1021/jacs.8b08100

Cited by 26 publications

(18 citation statements)

References 24 publications

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“…For example, synthesis of N-heterocycles via sensitization of azido compounds [30][31][32][33][34][35] and isomerization of alkenes [36][37][38] have been described. Also, alkene-alkene [2 + 2] cycloaddition for the synthesis of cyclobutanes in inter-and intramolecular fashion based on the EnT process has been reported [39][40][41][42][43][44][45][46] . Meanwhile, only a limited number of studies on the alkyne-alkene reactions with visible light photocatalysis have been reported.…”

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confidence: 99%

Alkyne–Alkene [2 + 2] cycloaddition based on visible light photocatalysis

Lee

Kwak

et al. 2020

Nat Commun

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UV-activated alkyne-alkene [2 + 2] cycloaddition has served as an important tool to access cyclobutenes. Although broadly adopted, the limitations with UV light as an energy source prompted us to explore an alternative method. Here we report alkyne-alkene [2 + 2] cycloaddition based on visible light photocatalysis allowing the synthesis of diverse cyclobutenes and 1,3-dienes via inter-and intramolecular reactions. Extensive mechanistic studies suggest that the localized spin densities at sp 2 carbons of alkenes account for the productive sensitization of alkenes despite their similar triplet levels of alkenes and alkynes. Moreover, the efficient formation of 1,3-dienes via tandem triplet activation of the resulting cyclobutenes is observed when intramolecular enyne cycloaddition is performed, which may serve as a complementary means to the Ru(II)-catalyzed enyne metathesis. In addition, the utility of the [2 + 2] cycloaddition has been demonstrated by several synthetic transformations including synthesis of various extended π-systems.

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confidence: 99%

Alkyne–Alkene [2 + 2] cycloaddition based on visible light photocatalysis

Lee

Kwak

et al. 2020

Nat Commun

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“…The well-studied system is singlet oxygen that can either undergo a [2+2]-photocycloaddition or an ene-reaction depending on the alkene reactant and conditions employed. 64,65 Based on this, Sivaguru and co-workers altered the reactivity of triplet excited alkenes towards photoene reaction 79 rather than a conventional [2+2]-photocycloaddition.…”

Section: Divergent Photoreactivity Of Imides With Alkenes: [2+2]-phot...mentioning

confidence: 99%

Using Restricted Bond Rotations to Enforce Excited-State Behavior of Organic Molecules

Kandappa¹,

Ahuja²,

Singathi³

et al. 2022

Synlett

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“…Interestingly, alternative reaction pathways to the more classical [2+2] cycloaddition, such as the photoene reaction, have recently been reported for citraconicimides. 20 Furthermore, although extensive ring rearrangements through competing pathways are also known, 21 the preparation of the dihydrooxepin-2(3 H )-one core by photochemical or indeed any other methods has not been reported.…”

Section: Table 1 Photochemical Reactions Carried Out In...mentioning

confidence: 99%

A Photochemical Microfluidic Reactor for Photosensitized [2+2] Cycloadditions

Bargum¹,

Krell-Jørgensen²,

Nielsen³

et al. 2022

Synlett

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Here we report a microfluidic system for photochemical cycloadditions fabricated using silicon micro processing technologies. The system was optimized to yield residence times of just a few minutes for a range of photochemical [2+2]-cycloaddition reactions facilitated using high power UV-LEDs at 375 nm and triplet photosensitizers, which removed the need for the low wavelengths typically required for these types of transformations. Adducts using different excitable olefins with different linear-, carbocyclic- and heterocyclic coupling partners were explored to demonstrate the feasibility of performing photochemistry in microflow in an academic research environment. Finally, a reaction leading to a novel dihydrooxepin-2(3H)-one scaffold, and a mechanistic proposal for its formation are reported.

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Realizing the Photoene Reaction with Alkenes under Visible Light Irradiation and Bypassing the Favored [2 + 2]-Photocycloaddition

Abstract: The textbook photoreaction between two alkenes is the [2 + 2]-photocycloaddition resulting in functionalized cyclobutanes. Herein, we disclose an unusual reactivity of alkenes that favor photoene reaction over the [2 + 2]-photocycloaddition.

Cited by 26 publications

References 24 publications

Alkyne–Alkene [2 + 2] cycloaddition based on visible light photocatalysis

Alkyne–Alkene [2 + 2] cycloaddition based on visible light photocatalysis

Using Restricted Bond Rotations to Enforce Excited-State Behavior of Organic Molecules

A Photochemical Microfluidic Reactor for Photosensitized [2+2] Cycloadditions

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