crossing yields an oxetane II. The ratio of nuclear spin polarizations in I and II strongly depends on temperature through the competition of nuclear spin relaxation in 3III with the biradical rearrangement. Using a kinetic treatment, a closed-form expression for the polarization ratio was derived. The activation energy of the cyclopropylmethyl−homoallyl rearrangement (17 ± 2 kJ/mol) was obtained from an
苯醌与降
冰片二
烯或
四环烷的 Paterno-Buchi 环加合物中的
化学诱导动态核自旋极化 (CIDNP) 源于具有
降冰片烯基亚结构的三重双自由基 3III。3III 的系间交叉和自由基末端的组合得到
氧杂
环丁烷 I。通过
环丙基甲基-高
烯丙基重排,3III 转化为 Paterno-Buchi 双自由基 3IV,在系间交叉后产生
氧杂
环丁烷 II。通过 3III 中的核自旋弛豫与双自由基重排的竞争,I 和 II 中的核自旋极化比率强烈依赖于温度。使用动力学处理,导出了极化比的封闭式表达式。