M. Helliwell, Y. You, J. Joule
Jun 1, 2006
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0
Influential Citations
4
Citations
Journal
Acta Crystallographica Section E-structure Reports Online
Abstract
5,6-Diethylpyrazin-2-one reacts with iodomethane to give a quaternary salt, deprotonation of which, in situ, liberates a 3-oxidopyrazinium which undergoes a 1,3-dipolar cycloaddition with methyl acrylate to form methyl (Z)-5-ethyl-4-ethylidene-8-methyl-2-oxo-3,8-diazabicyclo[3.2.1]octane-6-endo-6-carboxylate. The crystal structure revealed (i) the existence of the imine product as its enamine tautomer, (ii) the Z geometry of the exocyclic double bond, and (iii) the endo orientation of the ester group. Pairwise hydrogen bonding between the NH H atom and the amide carbonyl group links the molecules into centrosymmetric dimers.