Tandem polar/radical crossover sequences for the formation of fused and bridged bicyclic nitrogen heterocycles involving radical ionic chain reactions, and alkene radical cation intermediates, performed under reducing conditions: Scope and limitations
Tandem polar/radical crossover sequences for the formation of fused and bridged bicyclic nitrogen heterocycles involving radical ionic chain reactions, and alkene radical cation intermediates, performed under reducing conditions: Scope and limitations
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DOI：
10.1021/ja035639s
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发表时间：
2003-07-02
影响因子：
15
通讯作者：
Huang, XH
中科院分区：
文献类型：
--
作者：
Crich, D;Ranganathan, K;Huang, XH
它表明，磷酸化形式的β-硝基醇提供了一个很好的手段进入β-（磷酸氧基）烷基自由基暴露于三丁基氢化锡和AIBN在苯中回流。这些自由基，然后进行异裂的磷酸盐基团，产生烯烃自由基阳离子/磷酸根阴离子接触离子对被困在分子内的串联极性/自由基交叉序列涉及自由基离子链反应的烯丙基和炔丙基胺。烯烃自由基阳离子的取代模式决定了环化模式，并且当亲核攻击以内模式发生时，这可以通过初始外模式亲核环化或桥接双环系统被工程化以形成稠环系统。
It is demonstrated that phosphorylated forms of beta-nitro alcohols provide an excellent means of entry into beta-(phosphatoxy)alkyl radicals on exposure to tributyltin hydride and AIBN in benzene at reflux. These radicals then undergo heterolytic cleavage of the phosphate group to yield alkene radical cation/ phosphate anion contact ion pairs which are trapped intramolecularly in a tandem polar/radical crossover sequence involving radical ionic chain reactions by allylic and propargylic amines. The substitution pattern of the alkene radical cation dictates the cyclization mode, and this may be engineered to form fused ring systems by an initial exo-mode nucleophilic cyclization or bridged bicyclic systems when the nucleophilic attack takes place in the endo-mode.