A number of 3-hydroxy substituted indolic nitrones were found to quantitatively photorearrange to (2-benzoylamino)phenyl ketones upon UV-A irradiation. EPR-Spin Trapping experiments suggest that the process, which is believed to proceed via the formation of an oxaziridine, follows a homolytic pathway. Although DFT calculations do not allow to totally exclude alternative routes involving singlet intermediates, they do provide support to the proposed homolytic mechanism, which would be driven by a 1,5-hydrogen transfer subsequent to the oxaziridine ring opening. When this hydrogen transfer was made impossible by methylation of the 3-OH group, a benzoxazine was isolated as the sole reaction product. (C) 2011 Elsevier Ltd. All rights reserved.

Radical intermediates in the photorearrangement of 3-hydroxyindolic nitrones

Alberti Angelo;
2011

Abstract

A number of 3-hydroxy substituted indolic nitrones were found to quantitatively photorearrange to (2-benzoylamino)phenyl ketones upon UV-A irradiation. EPR-Spin Trapping experiments suggest that the process, which is believed to proceed via the formation of an oxaziridine, follows a homolytic pathway. Although DFT calculations do not allow to totally exclude alternative routes involving singlet intermediates, they do provide support to the proposed homolytic mechanism, which would be driven by a 1,5-hydrogen transfer subsequent to the oxaziridine ring opening. When this hydrogen transfer was made impossible by methylation of the 3-OH group, a benzoxazine was isolated as the sole reaction product. (C) 2011 Elsevier Ltd. All rights reserved.
2011
Istituto per la Sintesi Organica e la Fotoreattivita' - ISOF
Nitrone photochemistry
Oxaziridine intermediates
DFT calculations
EPR spectroscopy
Spin trapping
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/314801
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