Photo-Fries rearrangement of 1-pyrenyl esters

TETRAHEDRON LETTERS

卷:58

Article

Maeda, Hajime¹  Akai, Tomomi¹  Segi, Masahito¹ 

[1] Kanazawa Univ, Sch Chem, Coll Sci & Engn, Appl Chem Course, Kakuma Machi, Kanazawa, Ishikawa 9201192, Japan

关键词: Photorearrangement;    Photo-Fries rearrangement;    Pyrene;    Pyrenyl ester;    Intramolecular hydrogen bonding;   

DOI  :  10.1016/j.tetlet.2017.10.007

来源: Elsevier

【 摘 要 】

Photo-Fries rearrangement reactions of 1-pyrenyl esters were investigated. Photoreaction of 1-pyrenyl benzoate in benzene generates 1-hydroxy-2-pyrenyl phenyl ketone along with 1-pyrenol. The exceptionally down field H-1 NMR chemical shift of OH proton in the photoproduct indicates the existence of intramolecular hydrogen bonding. Photorearrangements of analogs that have electron-withdrawing or electron-releasing group on the phenyl ring, and related heteroaromatic carboxylates also take place to form the corresponding ketones. However, photoreactions of 1-pyrenyl aliphatic carboxylate esters do not occur. The results of spectroscopic and theoretical studies suggest the mechanistic pathway for this process is initiated by homolytic C-O bond cleavage in an aroyl group localized (1)(pi ->pi*) excited state of the 1-pyrenyl esters. The radical pair generated in this fashion then undergoes in-solvent-cage coupling to yield the 1-hydroxy-2-pyrenyl aryl ketone selectively. (C) 2017 Elsevier Ltd. All rights reserved.

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