Vyacheslav Diev - Esters of Feist’s Acid: Some Insights into the Electronic Structure and Reactivity of Methylenecyclopropanes Ring-Substituted with Acceptor Groups

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      Publication Details (including relevant citation   information):

      Eur.   J. Org. Chem.   2009, 525-530

      Abstract:

      1,3-Dipolar cycloaddition of C-aryl-N-aryl- or   N-methylnitrones with esters of Feist's acid   (3-methylenecyclopropane-trans-1,2-dicarboxylic acid)   occurs with the formation of the corresponding   spiro[cyclopropane-1,4-isoxazolidine] cycloadducts as single   isomer with yields in the range of 17–59 %. The reaction proceeds   with inverse regiochemical outcome compared to cycloadditions   with unsubstituted methylenecyclopropane. Feist's esters are   significantly less active towards cycloaddition with nitrones   than methylenecyclopropane and reactions require prolonged   heating at elevated temperature. The electronic structures of   Feist's esters were investigated by means of molecular   photoelectron spectroscopy and theoretical calculations   (HF/6-31G*, B3LYP/6-31G*). Both, measured photoelectron   HeI spectrum and ground state calculations (HF/6-31G*)   of Feist's esters, indicate considerable lowering of the   methylenecyclopropane π-**** energies by substitution with an   acceptor group. B3LYP calculations of addends and transition   states forthe interaction of methylenecyclopropane with   C,N-diphenylnitrone correctly predict   regiochemical outcome. However, B3LYP calculations do not account   for the observed regiochemical outcome and diminished reactivity   in reactions of Feist's esters with   C,N-diphenylnitrone.

      Address (URL): http://onlinelibrary.wiley.com/doi/10.1002/ejoc.200800975/abstract