Photochemistry of 2-nitrobenzylidene acetals
Jazyk angličtina Země Spojené státy americké Médium print
Typ dokumentu časopisecké články
PubMed
19824651
DOI
10.1021/jo901756r
Knihovny.cz E-zdroje
- MeSH
- acetaly chemie MeSH
- benzylidenové deriváty chemie MeSH
- chemické modely MeSH
- fotochemie * MeSH
- fotolýza MeSH
- kvantová teorie MeSH
- počítačová simulace MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- 2-nitrobenzylidene acetal MeSH Prohlížeč
- acetaly MeSH
- benzylidenové deriváty MeSH
Photolysis of dihydroxy compounds (diols) protected as 2-nitrobenzylidene acetals (ONBA) and subsequent acid- or base-catalyzed hydrolysis of the 2-nitrosobenzoic acid ester intermediates result in an efficient and high-yielding release of the substrates. We investigated the scope and limitations of ONBA photochemistry and expanded upon earlier described two-step procedures to show that the protected diols of many structural varieties can also be liberated in a one-pot procedure. In view of the fact that the acetals of nonsymmetrically substituted diols are converted into one of the corresponding 2-nitrosobenzoic acid ester isomers with moderate to high regioselectivity, the mechanism of their formation was studied using various experimental techniques. The experimental data were found to be in agreement with DFT-based quantum chemical calculations that showed the preferential cleavage occurs on the acetal C-O bond in the vicinity of more electron-withdrawing (or less electron-donating) groups. The study also revealed considerable complexity in the cleavage mechanism and that the structural variations in the substrate can significantly alter the reaction pathway. This deprotection strategy was found to be also applicable for 2-thioethanol when released from the corresponding monothioacetal in the presence of a reducing agent, such as ascorbic acid.
Citace poskytuje Crossref.org
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