Synthesis of Nitrogen Bridgehead Bicyclic Heterocycles via Ring-Closure of β-Ammonio 5-Hexenyl Radicals
作者:Ernest W. Della、Andrew M. Knill
DOI:10.1021/jo960886i
日期:1996.1.1
hyl radical (2), cyclizes essentially completely. Molecular mechanics calculations suggest that the increased activation barrier associated with ring-closure of 6 is the result of a higher than expected transition state energy. A study of the behavior of beta-ammonio-substituted 5-hexenyl radicals, such as the 3,3-dimethyl-3-azonia-5-hexenyl radical (22), reveals that cyclization occurs readily. Treatment
2-(3-亚甲基哌啶基)乙基(6)在其碳环类似物2-(3-亚甲基环己基)乙基(2)基本上完全环化的条件下表现出相当不愿闭环。分子力学计算表明,与6的闭环相关的增加的活化势垒是高于预期的过渡态能的结果。对β-铵取代的5-己烯基自由基的行为的研究,例如3,3-二甲基-3-氮杂-5-己烯基自由基(22),表明容易发生环化。在叔戊醇中用氢化三丁基锡处理1-甲基-1-(2-(苯基硒烯基)乙基)-3-亚甲基哌啶碘化物(20),得到桥头氮双环杂环化合物1,5-二甲基-1-氮杂双环[3.2] .1]辛烷碘化物(26),收率高,无污染,