Photogeneration of quinone methide from adamantylphenol in an ultrafast non-adiabatic dehydration reaction

Forjan, Mateo; Zgrablić, Goran; Vdović, Silvije; Šekutor, Marina; Basarić, Nikola; Kabaciński, Piotr; Pashaki, Maryam Nazari Haghighi; Frey, Hans‐Martin; Cannizzo, Andrea; Cerullo, Giulio

doi:10.1039/d1cp05690e

Cited by 3 publications

(2 citation statements)

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“…We investigated ultrafast dynamics of diazo derivatives on a homebuilt fs-TA experimental setup, which is detailed elsewhere . Briefly, 120 fs pulses at an 800 nm center wavelength at a 1 kHz repetition rate were generated using a Ti:sapphire regenerative amplifier system (Spitfire, Spectra-Physics).…”

Section: Experimental and Computational Detailsmentioning

confidence: 99%

“…We investigated ultrafast dynamics of diazo derivatives on a homebuilt fs-TA experimental setup, which is detailed elsewhere. 57 Briefly, 120 fs pulses at an 800 nm center wavelength at a 1 kHz repetition rate were generated using a Ti:sapphire regenerative amplifier system (Spitfire, Spectra-Physics). For the pump pulses, the fundamental beam was frequency doubled to give 400 nm and then mixed with the leftover fundamental beam to produce 267 nm via sum frequency generation.…”

Section: ■ Experimental and Computational Detailsmentioning

confidence: 99%

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Ultrafast Photoelimination of Nitrogen from Upper Excited States of Diazoalkanes and the Fate of Carbenes Formed in the Reaction

et al. 2023

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The photochemical reactivity of diphenyldiazomethane 1 and phenyl 1- and 2-adamantyl diazomethanes 2 and 3, respectively, was investigated by transient absorption spectroscopy (TA). Photoelimination of N2 upon UV excitation takes place in the anti-Kasha ultrafast photochemical reaction from the upper excited singlet states to deliver singlet carbenes, which were, in the case of 1 and 2, detected by fs-TA. The reactivity of the carbenes differs with respect to the substituent at the carbene center. The singlet car-1 in a nonpolar solvent delivers the triplet carbene by intersystem crossing (ISC). Singlet car-2 does not undergo ISC but reacts in the intermolecular insertion reactions into C–H bonds. Car-3 has an α-C–H bond next to the carbene center and reacts rapidly in the intramolecular C–H insertion reaction to deliver alkene, precluding its detection by fs-TA. However, the isolation of ketone photoproducts from 3 is highly indicative of triplet car-3’s intermediate formation. The TA spectra from the S1–S3 states of 1–3 were computed using time-dependent density functional theory, while the multiconfigurational perturbation theory to the second order was used for the absorption spectra of the corresponding singlet and triplet carbenes. The modeled and measured spectra are in good agreement, and the computations corroborate the assignments of the key short-lived intermediates.

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Section: Experimental and Computational Detailsmentioning

confidence: 99%

Section: ■ Experimental and Computational Detailsmentioning

confidence: 99%

Ultrafast Photoelimination of Nitrogen from Upper Excited States of Diazoalkanes and the Fate of Carbenes Formed in the Reaction

et al. 2023

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Photodehydration mechanisms of quinone methide formation from 2-naphthol derivatives

Forjan¹,

Vdović²,

Šekutor³

et al. 2022

Journal of Photochemistry and Photobiology A: Chemistry

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Different Reaction Mechanisms Triggered by the Meta Effect: Photoinduced Generation of Quinone Methides from Hydroxybiphenyl Derivatives

Guo,

Ge,

Phillips

et al. 2024

J. Phys. Chem. Lett.

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A series of sterically congested quinone methides (QMs) exhibit photoinduced antiproliferative activity against some human cancer cell lines. To elucidate the structure–reactivity relationship and details of mechanisms of the photogeneration of sterically congested QMs, we chose phenylphenol derivatives 1–3 as QM precursors and investigated their photodehydration processes in aqueous solutions using ultrafast spectroscopy and theoretical computations. We found that meta derivatives 1 and 2 undergo water-mediated excited-state proton transfer (ESPT) from the phenol OH, followed by expulsion of the OH– to form QMs. By comparison, para derivative 3 proceeds via water-mediated ESPT from H2O to benzyl alcohol coupled with dehydration as the first step, delivering a cation intermediate, which further deprotonates to yield QM. Such results would help chemists understand more about the meta effects in photochemistry and about ESPT and would help synthetic chemists design sterically congested QM precursors with extraordinary reactivities and expand applications of QMs in biological and medical systems.

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Photogeneration of quinone methide from adamantylphenol in an ultrafast non-adiabatic dehydration reaction

Abstract: The ultrafast photochemical reaction of quinone methide (QM) formation from adamantylphenol was monitored in real time using femtosecond transient absorption spectroscopy and fluorescence upconversion in solution at room temperature. Experiments...

Cited by 3 publications

References 40 publications

Ultrafast Photoelimination of Nitrogen from Upper Excited States of Diazoalkanes and the Fate of Carbenes Formed in the Reaction

Ultrafast Photoelimination of Nitrogen from Upper Excited States of Diazoalkanes and the Fate of Carbenes Formed in the Reaction

Photodehydration mechanisms of quinone methide formation from 2-naphthol derivatives

Different Reaction Mechanisms Triggered by the Meta Effect: Photoinduced Generation of Quinone Methides from Hydroxybiphenyl Derivatives

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