Direct observation and reactivity of transient ketenes generated by flash photolysis
作者:Annette D. Allen、John Andraos、A. J. Kresge、Michael A. McAllister、Thomas T. Tidwell
DOI:10.1021/ja00031a051
日期:1992.2
Nitroxyl Radical Reactions with 4-Pentenyl- and Cyclopropylketenes: New Routes to 5-Hexenyl- and Cyclopropylmethyl Radicals
作者:Annette D. Allen、Michael F. Fenwick、Huda Henry-Riyad、Thomas T. Tidwell
DOI:10.1021/jo0102922
日期:2001.8.1
in hydrocarbon solvents. The reactions of these ketenes with the nitroxylradicals tetramethylpiperidinyloxyl (TEMPO, TO*) and tetramethylisoindoline-2-oxyl (TMIO, IO*) form carboxy substituted 5-hexenyl and cyclopropylmethyl radicals which are either trapped by a second nitroxylradical or undergo rearrangements followed by trapping. The rate constant of the reaction of 4a with TEMPO was similar to
4-戊烯基酮4a和9以及环丙基烯酮3a,13、14(RCH = C = O)是通过光化学Wolff重排生成的,并且在室温下在烃类溶剂中被IR观察为相对长寿的物种。这些烯酮与硝基氧基四甲基哌啶基氧基(TEMPO,TO *)和四甲基异吲哚啉-2-氧基(TMIO,IO *)的反应形成羧基取代的5-己烯基和环丙基甲基,它们被第二个硝基氧基所俘获或进行重排通过诱捕。4a与TEMPO的反应速率常数与n-BuCH = C = O(1b)相似,而3a的反应速率高4.3倍,表明初始自由基的环丙基稳定性。