Structure and Chemistry of Malonylmethyl‐ and Succinyl‐Radicals. The search for homolytic 1,2‐rearrangements

Abstract Malonylmethyl radical I [· CH 2 CH(COOEt) 2 ] and its thioester analogue II [· CH 2 CH(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°C. At higher temperatures of up to 140°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°C in chlorobenzene to only a small extent.