Four　tetramethyl　4,4＇-(ethane-1,2-diylidene)bis[1-R-5-oxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate]　compounds,　denoted　class　(1),　are　a　series　of　conjugated　buta-1,3-dienes　substituted　with　a　heterocyclic　group.　The　compounds　can　be　used　as　dyes　and　pigments　due　to　their　long-range　conjugated　systems.　Four　structures　were　studied　using　H-1　NMR,　C-13　NMR　and　mass　spectroscopy,　viz.　with　R　=　2,4,6-trimethylphenyl,　(la),　R　=　cyclohexyl,　(1b),　R　=　tert-butyl,　(1c),　and　R　=　isopropyl,　(1d).　A　detailed　discussion　is　presented　regarding　the　characteristics　of　the　three-dimensional　structures　based　on　NMR　analysis　and　the　X-ray　crystal　structure　of　(1a),　namely　tetramethyl　4,4＇-(ethane-1,2-diylidene)bis[5-oxo-1-(2,4,6-trimethylpheny1)-　4,5-dihydro-1H-pyrrole-2,3-dicarboxylate],　C36H36N2O10.　Theconjugation　plane　and　stability　were　also　studied　via　quantum　chemical　calculations.