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Abstract A density functional theoretical (DFT) study is presented, implicating a1O2oxidation process to reach a dihydrobenzofuran from the reaction of the natural homoallylic alcohol, glycocitrine. Our results predict an interconversion between glycocitrine and aniso‐hydroperoxide intermediate [R(H)O+–O−] that provides a key path in the chemistry which then follows. Formations of allylic hydroperoxides are unlikely from a1O2‘ene’ reaction. Instead, the dihydrobenzofuran arises by1O2oxidation facilitated by a 16° curvature of the glycocitrine ring imposed by a pyramidalN‐methyl group. This curvature facilitates the formation of theiso‐hydroperoxide, which is analogous to theisospecies CH2I+–I−and CHI2+–I−formed by UV photolysis of CH2I2and CHI3. Theiso‐hydroperoxide is also structurally reminiscent of carbonyl oxides (R2C=O+–O−) formed in the reaction of carbenes and oxygen. Our DFT results point to intermolecular process, in which theiso‐hydroperoxide's fate relates to O‐transfer and H2O dehydration reactions for new insight into the biosynthesis of dihydrobenzofuran natural products.
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This content will become publicly available on March 25, 2026
Mechanistic and Curtin–Hammett Studies of the 1 O 2 Oxidation of a Prenyl Phenol and Phenolate Anion
ABSTRACT The Curtin–Hammett principle, widely recognized in thermal reactions, has been extended to photosensitization processes in this study, providing new insights into the reactivity of photogenerated singlet oxygen (1O2) with phenol and phenolate anion species. Here, we explore mechanistic and Curtin–Hammett studies of the equilibrium between the phenol and phenolate anion forms of a prenylated natural product, prenylphloroglucinol. This study uses density functional theory (DFT) to examine phenol and phenolate anion‐quenching pathways of1O2showing distinct pathways for each form. In the phenolate anion,1O2is quenched to form a peroxy anion. In contrast, in the phenol form,1O2leads to a potent epoxidizing agent in a seemingly pro‐oxidant path. Aniso‐hydroperoxyhydrofuran intermediate is proposed to be key in the epoxidation. Meanwhile, the phenolate anion cyclizes and protonates forming a comparatively benign hydroperoxyhydrofuran species. The phloroglucinol is next to the C‐prenyated group directs the reaction pathway towards the formation of a dihydrobenzofuran, deviating from the conventional1O2“ene” reaction mechanism and the production of allylic hydroperoxides typically observed in trisubstituted alkenes.
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- Award ID(s):
- 2154133
- PAR ID:
- 10582891
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Physical Organic Chemistry
- Volume:
- 38
- Issue:
- 5
- ISSN:
- 0894-3230
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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