277. Structure and Chemistry of Malonylmethyl- and Succinyl-Radicals. The Search for Homolytic 1,2-Rearrangements

Article abstract of DOI:10.1002/hlca.19830660843

Malonylmethyl radical I <.CH2CH(COOEt)2> and its thioester analogue II <.CH2CH(COOEt)(COSEt)> were generated by standard photolytic and thermolytic methods from perester and bromo precursors.The structures of I and II were examined by ESR spectroscopy and found to exist in preferred conformations.However, no indication for their rearrangement by 1,2-shift of either an ethoxycarboxyl or (ethylthio)carbonyl group to the corresponding succinyl radicals III and IV, respectively, was found at temperatures below -40 deg C.At higher temperatures of up to 140 deg C, the search for malonylmethyl -> succinyl rearrangement was examined by thorough-product analysis of the perester decomposition.There is evidence for the rearrangement of the radical I to III by photolysis and of the radical II to IV by thermolysis at 130 deg C in chlorobenzene to only a small extent.