Saraçoǧlu, N.Menzek, A.Sayan, Ş.Salzner, U.Balci, M.2016-02-082016-02-0819990022-3263http://hdl.handle.net/11693/25209Diels-Alder cycloaddition utilizing singlet oxygen as the dienophile with dimethyl cis-3,8-dihydroheptalene-3,8-dicarboxylate (5) has been investigated, and monoaddition product 7 has been isolated. The addition of a second singlet oxygen to the cycloheptatriene unit in 7 gave syn- bis(norcaradiene) bis(endoperoxide) 4. 1H NMR spectral studies and theoretical calculations indicate the increased pyramidalization in syn-4 compared with carbon analogue. The increased pyramidalization results from hyperconjugation between the central π-bond and the four adjacent C-O bonds and by rehybridization at C3, C4, C5, and C6. Furthermore, the increased reactivity for syn-4, which is probably arising from further folding of the central double bond, is also in agreement with theoretical calculations.EnglishDimethyl 3,8 dihydroheptalene 3,8 dicarboxylateEndoperoxideUnclassified drugChemical bindingConjugationDecarboxylationPeroxidationProton nuclear magnetic resonanceReaction analysisStructure analysisArticle10.1021/jo990393o