Structure and Chemistry of Malonylmethyl- and Succinyl-Radicals. The search for homolytic 1,2-rearrangements
作者:Urs Aeberhard、Reinhart Keese、Erich Stamm、Ulrich-Christian Vögeli、Willy Lau、Jay Kazuo Kochi
DOI:10.1002/hlca.19830660843
日期:1983.12.14
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
丙二酰基甲基基团I [·CH 2 CH(COOEt)2 ]及其硫代酯类似物II [·CH 2 CH(COOEt)(COSEt)]是通过标准的光解法和热解法从过酸酯和溴代前体生成的。通过ESR光谱检查了I和II的结构,发现它们以优选的构象存在。然而,没有迹象表明它们通过乙氧基羧基或(乙硫基)羰基的1,2-转移到相应的琥珀酰基基团III和IV而重排。分别在低于-40°C的温度下发现。在高达140°C的较高温度下,通过对过酸酯分解进行彻底的产物分析,研究了丙二酰甲基琥珀酰重排的过程。有证据表明,在130°C的氯苯中,通过光解作用将I - III自由基重排,通过在130°C下热解将II - IV自由基重排。