Attanasi OA, Caselli E, Davoli P, Favi G, Mantellini F, Ori C, Prati F. Alpha-aminoester-derived imidazoles by 1,5-electrocyclization of azavinyl azomethine ylides.
Org Lett 2009;
11:2840-3. [PMID:
19514726 DOI:
10.1021/ol901051z]
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Abstract
An efficient and practical method for the preparation of alpha-imidazol-1-yl esters from 1,2-diaza-1,3-dienes (DDs), alpha-amino esters, and aldehydes is described. The overall sequence features a Michael-type conjugate addition between the alpha-amino ester and the DD, followed by iminium ion formation via condensation with the aldehyde and 1,5-electrocyclization of the resulting thermally generated azavinyl azomethine ylide to afford eventually alpha-imidazol-1-yl esters. Such a protocol allows access to enantiomerically pure imidazoles from optically pure alpha-amino esters.
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