New Acridone- and (Thio)Xanthone-Derived 1,1-Donor-Acceptor-Substituted Alkenes: pH-Dependent Fluorescence and Unusual Photooxygenation Properties.
Molecules
; 26(11)2021 May 31.
Article
em En
| MEDLINE
| ID: mdl-34072791
ABSTRACT
A synthetic route to new heterocyclic 1,1-donor-acceptor-substituted alkenes starting with N-methyl-acridone, xanthone, and thioxanthone was investigated, leading to the acridone- and xanthone-derived products methyl 2-methoxy-2-(10-methylacridin-9 (10H)-ylidene)acetate (7) and methyl 2-methoxy-2-(9H-xanthen-9-ylidene)acetate (10) in low yields with the de-methoxylated product methyl 2-(10-methylacridin-9 (10H)-ylidene)acetate (8) and the reduced compound methyl 2-methoxy-2-(9H-xanthen-9-yl)acetate (11) as the major products from N-methyl acridone and xanthone. From thioxanthone, only the rearrangement and reduction products (14) and (15) resulted. The photophysical properties of compounds (7), (8), and (10) were investigated in the presence and absence of the Brønsted acid TFA by NMR, UV-VIS absorption, and fluorescence spectroscopy. Protonation of the acridone-derived alkenes (7) and (8) led to strong bathochromic and hyperchromic fluorescence shifts and a substantial increase in Stokes shift. The photooxygenation experiments with these substrates showed an unusual reactivity pattern in the singlet oxygen processes whereas the electron-rich enolether (7) was chemically unreactive, (8) and (10) were oxidatively cleaved, presumably via intermediate 1,2-dioxetanes.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Molecules
Assunto da revista:
BIOLOGIA
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Alemanha