Document Detail


Photochemistry of 2-nitrobenzylidene acetals.
MedLine Citation:
PMID:  19824651     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
Peter Sebej; Tom??s Solomek; L'ubica Hroudn??; Pavla Brancov??; Petr Kl??n
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of organic chemistry     Volume:  74     ISSN:  1520-6904     ISO Abbreviation:  J. Org. Chem.     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-11-13     Completed Date:  2010-01-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985193R     Medline TA:  J Org Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8647-58     Citation Subset:  IM    
Affiliation:
Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A8, 625 00 Brno, Czech Republic.
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MeSH Terms
Descriptor/Qualifier:
Acetals / chemistry*
Benzylidene Compounds / chemistry*
Computer Simulation
Models, Chemical
Photochemistry*
Photolysis
Quantum Theory
Chemical
Reg. No./Substance:
0/2-nitrobenzylidene acetal; 0/Acetals; 0/Benzylidene Compounds

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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