Carbene Formation by Extrusion of Nitrogen

Abdel‐Wahab, Aboel‐Magd A.; Ahmed, Saleh A.

doi:10.1002/chin.200417274

Cited by 2 publications

(3 citation statements)

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“…Diazoalkanes are versatile reagents in organic synthesis 5 that can undergo thermally or photochemically induced elimination of nitrogen to give carbenes. 6 Over the years, photogenerated carbenes have been used for the methylation of carboxylic acids, alcohols, phenols, heteroatoms including nitrogen and sulfur, cyclopropanations, ring expansions, and cycloadditions. 7 Photochemistry is particularly interesting since spatial and temporal control over the formation of carbenes may pave the road for applications in biological systems.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In this work, we focus on diazoalkanes 1 – 3 (Chart ) and demonstrate experimentally and computationally the general importance of higher excited singlet states in their photochemistry and photophysics. Diazoalkanes are versatile reagents in organic synthesis that can undergo thermally or photochemically induced elimination of nitrogen to give carbenes . Over the years, photogenerated carbenes have been used for the methylation of carboxylic acids, alcohols, phenols, heteroatoms including nitrogen and sulfur, cyclopropanations, ring expansions, and cycloadditions .…”

Section: Introductionmentioning

confidence: 99%

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Photoelimination of Nitrogen from Diazoalkanes: Involvement of Higher Excited Singlet States in the Carbene Formation

et al. 2020

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Although diazoalkanes are important carbene precursors in organic synthesis, a comprehensive mechanism of photochemical formation of carbenes from diazoalkanes has not been proposed. Synergy of experiments and computations demonstrates the involvement of higher excited singlet states in the photochemistry of diazoalkanes. In all investigated diazoalkanes, excitation to S1 results in nonreactive internal conversion to S0. On the contrary, excitation to higher-lying singlet states (Sn, n > 1), drives the reaction toward a different segment of the S1/S0 conical intersection seam and results in nitrogen elimination and formation of carbenes.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photoelimination of Nitrogen from Diazoalkanes: Involvement of Higher Excited Singlet States in the Carbene Formation

et al. 2020

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“…7,8 Moreover, significant endeavors were undertaken in the investigation of physical−organic aspects of carbene chemistry 9 and to elucidate carbene reaction mechanisms and reactivity. 10 One important reaction to generate carbenes is thermally or photochemically induced elimination of nitrogen from diazoalkanes, 11 which can also be used in biological systems. 12,13 Diazoalkanes are versatile reagents in organic synthesis.…”

Section: ■ Introductionmentioning

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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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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Carbene Formation by Extrusion of Nitrogen

Abstract: Organic chemistryOrganic chemistry Z 0200 Carbene Formation by Extrusion of Nitrogen -[168 refs.]. -(ABDEL-WAHAB, A.-M. A.; AHMED, S. A.; DURR, H.; CRC Handb. Org. Photochem. Photobiol. (2nd Ed.) 2004, 91/1-91/37; Dep. Chem., Assiut Univ., Assiut 71516, Egypt; Eng.) -Lindner 17-274

Cited by 2 publications

References 109 publications

Photoelimination of Nitrogen from Diazoalkanes: Involvement of Higher Excited Singlet States in the Carbene Formation

Photoelimination of Nitrogen from Diazoalkanes: Involvement of Higher Excited Singlet States in the Carbene Formation

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

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