Synthesis 2022; 54(20): 4576-4582
DOI: 10.1055/a-1874-4935
paper

Aryl Ketone Mediated Light-Driven Naphthylation of C(sp3)–H Bonds Attached to either Oxygen or Nitrogen Substituents

Masaya Azami
,
Toshihiro Murafuji
,
Shin Kamijo

This research was partially supported by the Japan Society for the Promotion of Science (JSPS, KAKENHI Grant Number JP22K05096).


Abstract

A light-driven naphthylation was achieved at C(sp3)–H bonds attached to either oxygen or nitrogen substituents using sulfonylnaphthalenes as a naphthalene precursor in the presence of 4-benzoylpyridine at ambient temperature. The present transformation is proposed to proceed through the generation of a carbon radical species via chemoselective cleavage of the heteroatom-substituted C(sp3)–H bond by photoexcited 4-benzoylpyridine, the addition of the derived carbon radical to the electron-deficient sulfonylnaphthalene, and then rearomatization by releasing sulfinyl radical.

Supporting Information



Publikationsverlauf

Eingereicht: 11. Mai 2022

Angenommen nach Revision: 13. Juni 2022

Accepted Manuscript online:
13. Juni 2022

Artikel online veröffentlicht:
02. August 2022

© 2022. Thieme. All rights reserved

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  • References


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  • 14 We, indeed, confirmed that the reaction of THF (1a) with 4-methoxy-1-(methylsulfonyl)naphthalene (2j) in the presence of 4-BzPy did not provide the expected product 3aj, and the recovery of a significant amount of the naphthalene precursor 2j was observed.
  • 15 The reason for the different reactivities of Ph2CO, 2-BzPy, 3-BzPy, and 4-BzPy is not clear at the moment.
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  • 20 We also measured the kinetic isotope effect (KIE) by treating a mixture of THF (1a) and its fully deuterated analogue 1a-d with the naphthalene precursor 2b under the optimized conditions. The value of the KIE was determined to be 1.6. A relatively small value of the KIE might indicate that the C–H bond cleavage by photoexcited 4-BzPy could be taking place in more concerted fashion, for instance, via electron transfer between photoexcited 4-BzPy and THF followed by proton abstraction. In any case, further investigations are required to clarify the detailed reaction pathway.
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