Unexpected Course of the Reaction of 2‐Unsubstituted 1 H ‐Imidazole 3‐Oxides with Ethyl Acrylate

The attempted ethenylation at C(2) of 2‐unsubstituted 1 H ‐imidazole N ‐oxides with ethyl acrylate (=prop‐2‐enoate) in the presence of Pd(OAc) 2 does not occur. In contrast to the other aromatic N ‐oxides, the [2+3] cycloaddition of imidazole N ‐oxides predominates, and 3‐hydroxyacrylates, isomeric...

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Bibliographic Details
Published in:Helvetica chimica acta 2012-04, Vol.95 (4), p.577-585
Main Authors: Mlostoń, Grzegorz, Urbaniak, Katarzyna, Wojciechowska, Alicja, Linden, Anthony, Heimgartner, Heinz
Format: Article
Language:English
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Summary:The attempted ethenylation at C(2) of 2‐unsubstituted 1 H ‐imidazole N ‐oxides with ethyl acrylate (=prop‐2‐enoate) in the presence of Pd(OAc) 2 does not occur. In contrast to the other aromatic N ‐oxides, the [2+3] cycloaddition of imidazole N ‐oxides predominates, and 3‐hydroxyacrylates, isomeric with the cycloadducts, are key products for the subsequent reaction. The final products were identified as dehydrated 2+1 adducts of 1 H ‐imidazole N‐ oxide and ethyl acrylate. The role of the catalyst is limited to the dehydration of the intermediate 3‐hydroxypropanoates to give 1 H ‐imidazol‐2‐yl‐substituted acrylates.
ISSN:0018-019X
1522-2675
DOI:10.1002/hlca.201100519